CN106232656B

CN106232656B - Michael acceptor-terminated urethane-containing fuel resistant prepolymers and compositions thereof

Info

Publication number: CN106232656B
Application number: CN201580020357.9A
Authority: CN
Inventors: R·凯莱德吉安; M·伊藤; 林仁和
Original assignee: PRC Desoto International Inc
Current assignee: PRC Desoto International Inc
Priority date: 2014-03-07
Filing date: 2015-03-06
Publication date: 2019-11-26
Anticipated expiration: 2035-03-06
Also published as: EP3114188B1; US20150252232A1; CN106232656A; AU2015226968A1; EP3470486A1; ES2707989T3; ES2981526T3; US9328274B2; EP3470486B1; JP2017510691A; WO2015134885A1; CA2942174A1; EP3114188A1; RU2016139299A; CA2942174C; KR20160130465A; JP6479055B2; RU2692804C2; AU2015226968B2; KR101909802B1

Abstract

Urethane-containing prepolymers formed from diisocyanates and suitable for michael addition cure chemistry and compositions thereof for sealant applications are disclosed. The prepolymer provides compositions that exhibit room temperature stability and controlled cure rates after brief activation.

Description

Michael acceptor-terminated urethane-containing fuel resistant prepolymers and compositions thereof

Technical Field

The present disclosure relates to michael acceptor-terminated urethane-containing prepolymers and compositions thereof for sealant applications. The prepolymer provides compositions that exhibit room temperature stability and controlled cure rate after brief (brief) activation.

Background

Sealants useful in aerospace and other applications must meet demanding mechanical, chemical and environmental requirements. The sealant can be applied to a variety of surfaces, including metal surfaces, primer coatings, midcoats, topcoats, and aged coatings.

Michael addition cure chemistry is often used in acrylic-based polymer systems and has also been tailored for use in polysulfide compositions as disclosed in U.S. patent No. 3138573. The use of michael addition cure chemistry for sulfur-containing polymers not only produces cured sealants with faster cure rates and enhanced properties, including resistance to fuel oil (fuel resistance) and heat resistance, but also provides sealants with improved physical properties, such as elongation. The use of michael addition cure chemistry for sulfur-containing polymer compositions useful in aerospace sealant applications is disclosed in U.S. application No.13/529237, filed on 21/6/2012, which is incorporated by reference in its entirety.

The compositions disclosed in U.S. patent No.13/529,237 use one or more base catalysts such as amine catalysts. In a suitable base such as 1, 8-diazabicycloundec-7-ene (DBU) or 1, 4-diazabicyclo [2.2.2]Octane (DABCO) or C_6-10The thiol-michael addition reaction is fast in the presence of primary amines, and the cure time is typically less than 2 hours. In the absence of a suitable base catalyst, the michael addition reaction, for example, between a thiol-terminated polythioether and a michael acceptor, is slow, providing a pot life of several days to several weeks depending on temperature. However, the physical properties of the cured composition are less than desirable for certain applications. The reaction mechanism for the thiol-Michael addition reaction is disclosed by Chan et al in Macromolecules 2010, 43, 6381-6388.

In practice, the foregoing compositions may be provided as a two-part (two-part) formulation, wherein the thiol-terminated compound and the michael acceptor are provided as separate components, with the amine catalyst in one or both of the components, and the two parts are mixed immediately prior to use. For example, if the catalytic amine is a tertiary amine, the amine catalyst may be in one or both of the components, and if the catalytic amine is a primary or secondary amine, the amine catalyst may be included only in the component containing the thiol-terminated compound, for example. Alternatively, the base catalyst may be provided as a third component, and the components containing the thiol-terminated compound, the component containing the michael acceptor and the component containing the base catalyst are combined and mixed just prior to use. However, once the components are mixed, the michael addition reaction proceeds and, depending at least in part on the temperature and type of amine catalyst, the pot life is limited to less than 2 hours. Furthermore, as the composition begins to cure, there is little ability to control the reaction rate to take advantage of the complex chemistry that occurs after the sealant is applied to the surface. Amine catalyzed systems such as those disclosed in U.S. Pat. No.6,172,179 typically cure in 2 to 12 hours and, while exhibiting acceptable fuel oil and heat resistance for many aerospace sealant applications, longer pot lives such as 24 to 72 hours and improved performance of the cured product are desirable.

Compositions having extended pot life and controlled cure rate can be achieved by using controlled release amine catalysts. In these systems, an amine catalyst such as a strong base or primary amine that produces a rapid reaction rate is protected or encapsulated and dispersed in the composition. Upon exposure, for example, to ultraviolet radiation, moisture, or temperature, the catalytic amine is released and catalyzes the michael addition reaction. In certain embodiments, such systems provide a pot life of greater than 2 hours to 12 hours and cure within 24-72 hours after a useful run time (working time). Controlled release amine catalysts have been used as described in U.S. patent No. 13/659,152, filed on 24/10/2012, which is incorporated by reference in its entirety. The use of a controlled release catalyst can provide the desired curing of the system (demand system). While the performance of cured sealants prepared using controlled release amine-catalyzed michael addition curable sulfur-containing polymer compositions is acceptable for many aerospace sealant applications, improved properties such as increased tensile strength are desirable.

SUMMARY

Michael acceptor-terminated urethane-containing prepolymers and the use of such prepolymers in sealant compositions having improved curing properties and controlled Michael addition reaction rates are disclosed.

In a first aspect, a michael acceptor-terminated urethane-containing prepolymer is provided that comprises the reaction product of reactants comprising (a) an isocyanate-terminated sulfur-containing adduct; and (b) comprises groups reactive with isocyanates; and at least one michael acceptor group.

In a second aspect, compositions are provided that include michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure; a thiol-terminated sulfur-containing prepolymer; and an amine catalyst.

In a third aspect, there is provided a method of synthesizing a michael acceptor-terminated urethane-containing prepolymer comprising reacting a thiol-terminated sulfur-containing adduct with a hydroxy vinyl ether to provide a hydroxy-terminated sulfur-containing adduct; reacting the hydroxyl-terminated sulfur-containing adduct with a polyisocyanate to provide an isocyanate-terminated urethane-containing adduct; and reacting the isocyanate-terminated urethane-containing adduct with a compound comprising a group reactive with isocyanate and at least one michael acceptor group to provide a michael acceptor-terminated urethane-containing prepolymer.

Reference is now made to certain embodiments of the compositions and methods. The disclosed embodiments are not intended to limit the claims. On the contrary, the claims are intended to cover all modifications, variations, and equivalents.

Brief Description of Drawings

Fig. 1 illustrates a reaction scheme for preparing michael acceptor-terminated urethane-containing prepolymers according to certain embodiments of the present disclosure.

Detailed Description

For the purposes of the following description, it is to be understood that the embodiments provided in this disclosure may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in the examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of about 1 and the recited maximum value of about 10, that is, having a minimum value equal to or greater than about 1 and a maximum value of equal to or less than about 10. Also, in this application, the use of "or" means "and/or" unless explicitly stated otherwise, even though "and/or" may be explicitly used in some instances.

A dash ("-") that is not between two letters or symbols is used to indicate a substituent or a point of covalent bonding between two atoms. For example the chemical group-CONH₂Is covalently bonded to another chemical moiety through a carbon atom. In some cases, the expression "-" is used to indicate the point of bonding.

"alkylaromatic hydrocarbon" refers to a hydrocarbon radical having one or more aryl and/or arenediyl groups and one or more alkyl and/or alkanediyl groups, wherein aryl, arenediyl, alkyl and alkanediyl groups are defined herein. In certain embodiments, each aryl and/or arene diyl group is C_6-12，C_6-10And in certain embodiments phenyl or phenyl diyl. In certain embodiments, each alkyl and/or alkanediyl is C_1-6，C_1-4，C_1-3And in certain embodiments methyl, methanediyl, ethyl or ethane-1, 2-diyl. In certain embodiments, the alkane aromatic group is C_4-18Alkane-arene C_4-16Alkane-arene C_4-12Alkane-arene C_4-8Alkane-arene C_6-12Alkane-arene C_6-10Alkane aromatic hydrocarbons and in certain embodiments C_6-9An alkane aromatic hydrocarbon. Examples of the alkane aromatic group include diphenylmethane.

"Alkanediyl" refers to a diradical of an alkarylene radical. In certain embodiments, the alkylaromatic diyl group is C_4-18Alkane-arene diyl, C_4-16Alkane-arene diyl, C_4-12Alkane-arene diyl, C_4-8Alkane-arene diyl, C_6-12Alkane-arene diyl, C_6-10An alkylaromatic diyl group, and in certain embodiments C_6-9An alkylaromatic diyl group. Examples of the alkylaromatic diyl group include diphenylmethane-4, 4' -diyl.

"Alkanediyl" refers to a diradical of a saturated, branched or straight chain acyclic hydrocarbon radical having, for example, 1-18 carbon atoms (C)_1-18) 1 to 14 carbon atoms (C)_1-14) 1 to 6 carbon atoms (C)_1-6) 1 to 4 carbon atoms (C)_1-4) Or 1 to 3 hydrocarbon atoms (C)_1-3). It is understood that branched alkanediyl has a minimum of three carbon atoms. In certain embodiments, the alkanediyl is C_2-14Alkanediyl, C_2-10Alkanediyl, C_2-8Alkanediyl, C_2-6Alkanediyl, C_2-4Alkanediyl and, in certain embodiments, C_2-3An alkanediyl group. Examples of alkanediyl include methane-diyl (-CH)₂-, ethane-1, 2-diyl (-CH)₂CH₂-, propane-1, 3-diyl and isopropane-1, 2-diyl (e.g. -CH)₂CH₂CH₂-and-CH (CH)₃)CH₂-, butane-1, 4-diyl (-CH)₂CH₂CH₂CH₂-, pentane-1, 5-diyl (-CH)₂CH₂CH₂CH₂CH₂-, Hexane-1, 6-diyl (-CH)₂CH₂CH₂CH₂CH₂CH₂-), heptane-1, 7-diyl, octane-1, 8-diyl, nonane-1, 9-diyl, decane-1, 10-diyl, dodecane-1, 12-diyl, and the like.

"Alkanoalkane" means a saturated hydrocarbon group having one or more cycloalkyl and/or cycloalkdiyl groups and one or more alkyl and/or alkanediyl groups, wherein cycloalkyl, cycloalkdiyl, alkyl and alkanediyl groups are defined herein. In certain embodiments, each cycloalkyl and/or cycloalkadiyl is C_3-6，C_5-6And in certain embodiments cyclohexyl or cyclohexanediyl. In certain embodiments, each alkyl and/or alkanediyl is C_1-6，C_1-4，C_1-3And in certain embodiments methyl, methanediyl, ethyl, or ethane-1, 2-diyl. In certain embodiments, the alkylcycloalkane group is C_4-18Alkane cycloalkane, C_4-16Alkane cycloalkane, C_4-12Alkane cycloalkane, C_4-8Alkane cycloalkane, C_6-12Alkane cycloalkane, C_6-10Alkane cycloalkanes and in certain embodiments are C_6-9Alkane cycloalkane. Examples of the alkane cycloalkane group include 1,1,3, 3-tetramethylcyclohexane and cyclohexylmethane.

"Alkanoalkandiyl" refers to a diradical of an alkanyl cycloalkane group. In certain embodiments, the alkanecycloalkanediyl is C_4-18Alkanecycloalkanediyl, C_4-16Alkanecycloalkanediyl, C_4-12Alkanecycloalkanediyl, C_4-8Alkanecycloalkanediyl, C_6-12Alkanecycloalkanediyl, C_6-10Alkanecycloalkanediyl and, in certain embodiments, C_6-9Alkane cycloalkanediyl group. Examples of the alkane cycloalkanediyl group include a1, 1,3, 3-tetramethylcyclohexane 1, 5-diyl group and a cyclohexylmethane-4, 4' -diyl group.

"alkenyl" means having the structure-CR ═ CR₂Wherein the alkenyl group is a terminal group and is bonded to a larger molecule. In such embodiments, each R may be selected from, for example, hydrogen and C_1-3An alkyl group. In certain embodiments, each R is hydrogen, and the alkenyl group has the structure-CH ═ CH₂。

"alkoxy" refers to the group-OR, where R is alkyl as defined herein. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy and n-butoxy. In certain embodiments, the alkoxy group is C_1-8Alkoxy radical, C_1-6Alkoxy radical, C_1-4Alkoxy and in certain embodiments is C_1-3An alkoxy group.

"alkyl" refers to a saturated, branched, or straight chain, monocyclic hydrocarbon radical having, for example, 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. It is understood that branched alkyl groups have a minimum of three carbon atoms. In certain embodiments, the alkyl group is C_1-6Alkyl radical, C_1-4Alkyl and in certain embodiments C_1-3An alkyl group. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, n-decyl, tetradecyl and the like. In certain embodiments, the alkyl group is C_1-6Alkyl radical, C_1-4Alkyl and in certain embodiments C_1-3An alkyl group. It is understood that branched alkyl groups have at least three carbon atoms.

"Cycloalkanediyl" refers to a diradical of a saturated monocyclic or polycyclic hydrocarbon group. In certain embodiments, the cycloalkanediyl group is C_3-12Cycloalkanediyl group, C_3-8Cycloalkanediyl group, C_3-6Cycloalkanediyl and, in certain embodiments, C_5-6A cycloalkanediyl group. Examples of the cycloalkanediyl group include cyclohexane-1, 4-diyl group, cyclohexane-1, 3-diyl group and cyclohexane-1, 2-diyl group.

"cycloalkyl" refers to a saturated monocyclic or polycyclic hydrocarbon mono-radical. In certain embodiments, cycloalkyl is C_3-12Cycloalkyl radical, C_3-8Cycloalkyl radical, C_3-6Cycloalkyl and in certain embodiments is C_5-6A cycloalkyl group.

"Heteroalkanediyl" refers to alkanediyl in which one or more carbon atoms are replaced by a heteroatom such as N, O, S or P. In certain embodiments of heteroalkyldiyl, the heteroatom is selected from N and O.

"Heteroalkylaromatic diyl" refers to an alkylaromatic diyl in which one or more carbon atoms are replaced by heteroatoms such as N, O, S or P. In certain embodiments of the heteroalkanenediyl, the heteroatom is selected from N and O.

"Heterocycloalkyldiyl" refers to a cycloalkanediyl group in which one or more carbon atoms are replaced by a heteroatom such as N, O, S or P. In certain embodiments of heterocycloalkanediyl, the heteroatom is selected from N and O.

"derived from" refers to a functional group or moiety after reaction with another reactive functional group or moiety. Such as the moiety-CH₂-CH₂-S-may be derived from alkenyl, -CH ═ CH₂Reaction with a thiol group-SH. Similarly, the moiety-S-may result from the reaction of-SH with a group reactive with a thiol group. In certain embodiments, the group-R' -results from the reaction of the group-R with a reactive group. In certain embodiments, the moiety-R' results from the reaction of compound R with a reactive group.

The core of the sulfur-containing prepolymer or adduct refers to the portion that forms the sulfur-containing prepolymer or adduct without terminal functional groups. For example having the structure R^f-R-R^fWherein each R is a member of the sulfur-containing prepolymer or adduct core^fRepresenting a moiety containing a terminal functional group) is-R-.

The core of a diisocyanate refers to the moiety that forms a diisocyanate without isocyanate groups. For example, the core of a diisocyanate having the structure O ═ C ═ N-R ═ C ═ O is represented by — R-.

"Michael acceptor" refers to an activated alkene, an alkenyl group adjacent to an electron withdrawing group such as, for example, a ketone, a halogen, a carbonyl (-CO), a nitro (-NO)₂) Nitrile (-CN), alkoxycarbonyl (-COOR), phosphonate (-PO (OR)₂) Trifluoromethyl (-CF)₃) Sulfonyl (-SO)₂-, trifluoromethanesulfonyl (-SO)₂CF₃) Or p-toluenesulfonyl (-SO)₂-C₆H₄-CH₃). In certain embodiments, the Michael acceptor group is selected from vinyl ketones, vinyl sulfones, quinones, enamines, ketimines, aldimines, oxazolidinesAnd acrylates. In certain embodiments, the michael acceptor or michael acceptor group does not include an acrylate.

"Michael acceptor compound" refers to a compound that contains at least one Michael acceptor group. In certain embodiments, the Michael acceptor compound is a divinyl sulfone, and the Michael acceptor group is a vinylsulfonyl group, e.g., -S (O)₂-CH＝CH₂. Other examples of michael acceptors are disclosed in Mather et al, prog.polym.sci., 2006, 31, 487-531 and include acrylates, acrylonitriles, acrylamides, maleimides, alkyl methacrylates, cyanoacrylates. Types of compounds that act as michael acceptors include vinyl ketones, quinones, nitroolefins, acrylonitriles, acrylates, methacrylates, cyanoacrylates, acrylamides, maleimides, dialkyl vinyl phosphonates and vinyl sulfones. Other Michael acceptors include vinyl ketones, α, β -unsaturated aldehydes, vinyl phosphonates, acrylonitrile, vinyl pyridine, certain azo compounds, β -ketoacetylene and acetylene esters. In certain embodiments, the Michael acceptor compound is a divinyl sulfone, and the Michael acceptor group is a vinylsulfonyl group, i.e., -S (O)₂-CH＝CH₂. In certain embodiments, the Michael acceptor compound is a bis (vinylsulfonyl) alkanol, and the Michael acceptor group is a 1- (ethylenesulfonyl) -n- (vinylsulfonyl) alkanol, i.e., -CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH＝CH₂And in certain embodiments, 1- (ethylenesulfonyl) -3- (vinylsulfonyl) propan-2-ol (-CH)₂-CH₂-S(O)₂-CH₂-CH(-OH)-CH₂-S(O)₂-CH＝CH₂)。

Michael acceptor compounds having more than one Michael acceptor group are also known. Examples include diacrylates such as ethylene glycol diacrylate and diethylene glycol diacrylate, dimethacrylates such as ethylene glycol methacrylate and diethylene glycol methacrylate, bismaleimides such as N, N '- (1, 3-phenylene) bismaleimide and 1, 1' - (methylenebis-4, 1-phenylene) bismaleimide, vinyl sulfones such as divinyl sulfone and 1, 3-bis (vinylsulfonyl) -2-propanol, and the like. In certain embodiments, the michael acceptor group has the structure of formula (1a) or formula (1 b):

-CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH＝CH₂ (1a)

-CH₂-CH₂-S(O)₂-CH₂-CH(-OH)-CH₂-S(O)₂-CH＝CH₂ (1b)

wherein each R¹⁰Independently selected from C_1-3An alkanediyl group.

"Metal ligand" refers to an ion or molecule that binds to a metal atom and potentially other atoms to form a coordination complex. The bonding between the metal and or atom typically includes the donation of one or more electron pairs to the metal, and may be covalent or ionic in nature. The metal ligands provided by the present disclosure are capable of forming coordination complexes to aerospace surfaces, such as aluminum and titanium surfaces, which can oxidize. In the case of an oxidized surface, the metal ligand may form a coordination complex with a metal such as al (iii) and an oxygen atom. The coordination complex may enhance adhesion of the coating or sealant to the metal or oxidized metal surface.

The metal ligand may be incorporated into the backbone of the prepolymer. Such reactive metal ligands may be commercially available or may be derived to include appropriate reactive substituents using methods known to those skilled in the art. Examples of sulfur-containing polymers incorporating metal ligands are disclosed in U.S. application No.13/923903 filed on 21.6.2013 and U.S. application No.14/065554 filed on 29.10.2013, each of which is incorporated herein by reference in its entirety.

Hydroxypyridones comprise groups such as 3-hydroxy-4-pyridone and 3-hydroxy-2-pyridone, which have the structure of formula (2a) or formula (2b), respectively:

wherein R is an organic group such as an alkyl group. The metal ligand derived from hydroxypyridone comprises a hydroxypyridone group and one or more reactive functional groups, such as a terminal thiol group.

"acetylacetonate (acetyl acetate) group" refers to a group having the structure:

in certain embodiments, acetylacetonate refers to a metal chelator comprising an acetylacetonate ligand and one or more reactive functional groups. In certain embodiments, the one or more reactive functional groups may be reactive with a thiol group, e.g., an epoxy group, an alkenyl group, a Michael acceptor group, or a group containing saturated carbon with a leaving group, which are particularly suitable for nucleophilic substitution, e.g., such as-Cl, -Br, -I, -OSO₂CH₃(methanesulfonate group), -OSO₂-C₆H₄-CH₃(tosylate) and the like.

"quinone" refers to a compound having a fully conjugated cyclic diketone structure derived from an aromatic compound by converting an even number of-CH ═ groups to-C (═ O) -groups (with any necessary rearrangement of the double bonds). Examples of quinones include 1, 2-benzoquinone, 1, 4-naphthoquinone and 9, 10-anthraquinone. The quinone group may be a metal ligand.

"maleimide" refers to a compound having a maleimide group:

bismaleimide refers to a compound having two maleimide groups bonded through a nitrogen atom via a linker. The maleimide-terminated sulfur-containing prepolymer is disclosed in U.S. application No.14/065499 filed on 29/10.2013, which is hereby incorporated by reference in its entirety.

"bis (sulfonyl) alkanol group" refers to a group having the general formula (4):

-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂- (4)

wherein each R¹⁰Independently selected from C_1-3An alkanediyl group. In certain embodiments, the bis (sulfonyl) alkanol group has the structure-CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH₂-CH₂-, and in certain embodiments, -CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH＝CH₂。

In certain embodiments, a "bis (sulfonyl) alkanol group" may be a monovalent bis (sulfonyl) alkanol group or a divalent bis (sulfonyl) alkanol group. In certain embodiments, the monovalent bis (sulfonyl) alkanol may be a terminal bis (sulfonyl) alkanol group such as a "1- (ethylenesulfonyl) -n- (vinylsulfonyl) alkanol group. The "terminal bis (sulfonyl) alkanol group may result from the reaction of a bis (sulfonyl) alkanol and may have a terminal portion (which has the general structure R)^8’-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-R⁸Wherein R is^8’Is derived from R⁸And R⁸A reactive moiety of a reactive moiety; each R¹⁰Independently selected from C_1-3An alkanediyl group. In certain embodiments, each R is⁸Includes a reactive functional group, and in certain embodiments is-CH ═ CH₂. In certain embodiments, the terminal bis (sulfonyl) alkanol group is a 1- (ethylenesulfonyl) -n- (vinylsulfonyl) alkanol group, such as 1- (ethylenesulfonyl) -3- (vinylsulfonyl) propan-2-ol, i.e., -CH₂-CH₂-S(O)₂-CH₂-CH(-OH)-CH₂-S(O)₂-CH＝CH₂. In certain embodiments, the terminal bis (sulfonyl) alkanol group has the structure-CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH＝CH₂。

In certain embodiments, the bis (sulfonyl) alkanol group may be divalent, such as when the group is incorporated into the backbone of a prepolymer (e.g., the sulfur-containing prepolymers and adducts disclosed herein). In certain embodiments, the divalent bis (sulfonyl) alkanol group may have the general structure-R^8’-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-R^8’-; in certain embodiments, -CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH₂-CH₂-, in certain embodiments, -R^8’-S(O)₂-CH₂-CH(-OH)-CH₂-S(O)₂-R^8’-, and in certain embodiments, -CH₂-CH₂-S(O)₂-CH₂-CH(-OH)-CH₂-S(O)₂-CH₂-CH₂-, wherein R^8’And R¹⁰As defined herein. In certain embodiments of the bis (sulfonyl) alkanol, each R is⁸Is an alkenyl radical, each R^8’Is an ethane-diyl group and/or each R¹⁰Is a methane-diyl group.

"bis (sulfonyl) alkanol" refers to the general formula R⁸-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-R⁸Wherein each R is⁸Is a moiety having a reactive functional group; and each R¹⁰Independently selected from C_1-3An alkanediyl group. In certain embodiments, each R is⁸Containing terminal groups reactive with thiol groups, e.g. such as alkenyl, epoxy, Michael acceptor groups, or groups containing saturated carbon with a leaving group, which are particularly suitable for nucleophilic substitution, e.g. such as-Cl, -Br, -I, -OSO₂CH₃(methanesulfonate group), -OSO₂-C₆H₄-CH₃(tosylate) and the like. In certain embodiments, the bis (sulfonyl) alkanol may be a bis (vinylsulfonyl) alkanol comprising a terminal alkenyl group. In thatIn certain embodiments, the bis (sulfonyl) alkanol may be where R⁸Bis (vinylsulfonyl) alkanols comprising a terminal alkenyl group, e.g. of the formula CH₂＝CH-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH＝CH₂The compound of (1). In certain embodiments, the bis (vinylsulfonyl) alkanol is 1, 3-bis (vinylsulfonyl) -2-propanol. In certain embodiments, the bis (sulfonyl) alkanol-containing compound may be prepared by reacting a bis (vinylsulfonyl) alkanol with a compound having a reactive end functional group and an end group (e.g., a thiol group or an epoxy group) reactive with a terminal alkenyl group of the bis (vinylsulfonyl) alkanol. In such embodiments, the bis (sulfonyl) alkanol may have structure R^8’-CH₂-CH₂-S(O)₂-R¹⁰-CH(-OH)-R¹⁰-S(O)₂-CH₂-CH₂-R^8’Wherein each R is^8’Is the moiety resulting from the reaction of the compound with the terminal alkenyl group of the bis (vinylsulfonyl) alkanol.

As used herein, "polymer" refers to oligomers, homopolymers and copolymers, which may be cured or uncured. Unless otherwise indicated, molecular weight is the number average molecular weight of the polymeric material, denoted as "Mn", which is measured, for example, by gel permeation chromatography using polystyrene standards in a manner recognized in the art. Unless otherwise indicated, molecular weight is the number average molecular weight of the polymeric material, denoted as "Mn", which is measured, for example, by gel permeation chromatography using polystyrene standards in a manner recognized in the art.

"prepolymer" refers to a polymer prior to curing. Generally, the prepolymers provided by the present disclosure are liquid at room temperature. "adduct" may refer to a prepolymer functionalized with reactive end groups; however, the prepolymer may also contain terminal functional groups. Thus, the terms prepolymer and adduct are used interchangeably. The term adduct is often used to denote a prepolymer which is an intermediate in the reaction sequence used to prepare the prepolymer.

' DouThioether "means a compound containing at least two thioether linkages, which is" -CR₂-S-CR₂- "group. In addition to at least two thioether groups, the polythioethers provided by the present disclosure can comprise at least two formal, acetal, and/or ketal groups, e.g., at least two-O-CR groups₂-O-group, wherein each R is independently selected from hydrogen, C_1-6Alkyl radical, C_7-12Phenylalkyl, substituted C_7-12Phenylalkyl, C_6-12Cycloalkylalkyl, substituted C_6-12Cycloalkylalkyl radical, C_3-12Cycloalkyl, substituted C_3-12Cycloalkyl radical, C_6-12Aryl and substituted C_6-12And (4) an aryl group. In certain embodiments, such compounds are prepolymers or adducts. Suitable polythioethers are disclosed, for example, in U.S. patent No.6172179, which is incorporated herein by reference in its entirety.

"substituted" refers to groups in which one or more hydrogen atoms are each independently substituted with the same or different substituents. In certain embodiments, the substituent is selected from the group consisting of halogen, -S (O)₂OH，-S(O)₂-SH, -SR (where R is C)_1-6Alkyl), -COOH, -NO₂，-NR₂(wherein each R is independently selected from hydrogen and C_1-3Alkyl), -CN, -C ═ O, C_1-6Alkyl, -CF₃-OH, phenyl, C_2-6Heteroalkyl group, C_5-6Heteroaryl group, C_1-6Alkoxy, and-COR (wherein R is C)_1-6Alkyl groups). In certain embodiments, the substituents are selected from-OH, -NH₂And C_1-3An alkyl group.

Reference is now made to certain embodiments of michael acceptor-terminated urethane-containing prepolymers (such as michael acceptor-terminated urethane-containing polythioethers), compositions thereof, and methods of synthesis. The disclosed embodiments are not intended to limit the claims. On the contrary, the claims are intended to cover all modifications, variations, and equivalents.

Michael acceptor-terminated urethane-containing prepolymers containing urethane segments (segments) incorporated into the backbone are disclosed. Michael acceptor-terminated urethane-containing prepolymers are useful in providing sealants having enhanced tensile strength.

The michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure exhibit improvements over previously disclosed michael acceptor-terminated sulfur-containing prepolymers, such as those disclosed in U.S. application nos. 13/529,237 and 13/659,152. Cured sealants prepared from michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure exhibit enhanced tensile strength and surface adhesion compared to michael acceptor-terminated sulfur-containing prepolymers disclosed in those applications. Enhanced tensile strength is believed to be imparted and improved surface adhesion by incorporating urethane segments into the polymer backbone is believed to result from the end-capping of groups that act as both metal ligands and michael acceptors.

The michael acceptor-terminated urethane-containing prepolymer comprises a urethane-containing and sulfur-containing backbone that is terminated with isocyanate groups that are further terminated with michael acceptor groups.

The michael acceptor-terminated urethane-containing prepolymer includes polythioethers, polysulfides, and combinations of any of the foregoing. In certain embodiments, the sulfur-containing prepolymer may be difunctional, and in certain embodiments, may have a functionality of greater than 2, such as 3, 4, 5, or 6. The sulfur-containing prepolymer may comprise a mixture of sulfur-containing prepolymers having different functionalities characterized by an average functionality of from 2.05 to 6, from 2.1 to 4, from 2.1 to 3, from 2.2 to 2.8, and in certain embodiments, from 2.4 to 2.6.

It will be appreciated that the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure may be synthesized by a number of routes. The functional groups of the precursors can be tailored and selected for a particular reaction chemistry. For example, in certain embodiments, it may be convenient for the sulfur-containing prepolymer to contain thiol or hydroxyl functional groups. In embodiments where the sulfur-containing prepolymer has functional hydroxyl groups, the diisocyanate may be reacted directly with the sulfur-containing prepolymer. In embodiments where the precursor sulfur-containing prepolymer is thiol-terminated, the thiol groups may be terminated with a hydroxyl-functional compound to provide a hydroxyl-terminated sulfur-containing prepolymer, which may then be reacted with a diisocyanate.

Examples of suitable polythioethers are disclosed, for example, in U.S. Pat. No.6,172,179.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer comprises a polythioether comprising a backbone comprising the structure of formula (5):

-R¹-[-S-(CH₂)₂-O-[-R²-O-]_m-(CH₂)₂-S-R¹]_n- (5)

wherein,

each R¹Independently selected from C_2-10N-alkanediyl radical, C_3-6Branched alkanediyl radical, C_6-8Cycloalkanediyl group, C_6-10Alkanecycloalkanediyl group, heterocyclic group, - [ (-CHR)³-)_p-X-]_q-(CHR³)_rA group in which each R is³Selected from hydrogen and methyl;

each R²Independently selected from C_2-10N-alkanediyl radical, C_3-6Branched alkanediyl radical, C_6-8Cycloalkanediyl group, C_6-14An alkanecycloalkanediyl group, a heterocyclic group, and- [ (-CH)₂-)_p-X-]_q-(CH₂)_r-a group;

each X is independently selected from O, S, and-NR-wherein R is selected from hydrogen and methyl;

m ranges from 0 to 50;

n is an integer from 1 to 60;

p is an integer from 2 to 6;

q is an integer of 1 to 5; and

r is an integer from 2 to 10.

In certain embodiments of the compounds of formula (5), R¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-wherein each X is independently selected from-O-and-S-. In certain embodiments, wherein R is¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, each X is-O-and in certain embodiments, each X is-S-.

In certain embodiments of the compounds of formula (5), R¹Is- [ - (CH)₂)_s-X-]_q-(CH₂)_r-, wherein each X is independently selected from-O-and-S-. In certain embodiments, wherein R is¹Is- [ - (CH)₂)_s-X-]_q-(CH₂)_r-, each X is-O-and in certain embodiments, each X is-S-.

In certain embodiments, R in formula (5)¹Is- [ (-CH)₂-)_p-X-]_q-(CH₂)_r-, where p is 2, X is O, q is 2, R is 2, R is²Is ethanediyl, m is 2, and n is 9.

In certain embodiments of formula (5), each R¹Derived from dimercaptodioxaoctane (DMDO) and, in certain embodiments, each R¹From dimercaptodiethylsulfide (DMDS).

In certain embodiments of formula (5), each m is independently an integer from 1 to 3. In certain embodiments, each m is the same and is 1,2, and in certain embodiments, 3.

In certain embodiments of formula (5), n is an integer from 1 to 30, an integer from 1 to 20, an integer from 1 to 10, and in certain embodiments, an integer from 1 to 5. Furthermore, in certain embodiments, n can be any integer from 1 to 60.

In certain embodiments of formula (5), each p is independently selected from 2, 3, 4, 5, and 6. In certain embodiments, each p is the same and is 2, 3, 4, 5, or 6.

Polysulfide refers to a prepolymer that contains one or more sulfide linkages in the polymer backbone and/or in pendant positions of the prepolymer chain, i.e., -S_x-a linker, wherein x is 2-4. In certain embodiments, the polysulfide prepolymer will have two or more sulfur-sulfur linkages. Suitable polysulfides are known by the names Thiokol-LP andcommercially available from, for example, Akzo Nobel and Toray Fine Chemicals.The products are obtained in a wide range of molecular weights, for example from less than 1100 to over 8000, and the molecular weight is the average molecular weight in g/mol. In some cases, the polysulfide has a number average molecular weight of 1000 daltons to 4000 daltons. Examples of suitable polysulfides are disclosed, for example, in U.S. patent No.4,623,711.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer comprises a michael acceptor-terminated urethane-containing prepolymer comprising a metal ligand, wherein the metal ligand is incorporated into the backbone of the prepolymer. Metal-ligand containing sulfur-containing prepolymers are disclosed in us patent No.14/065,554 filed on 29/10.2013, which is incorporated by reference in its entirety.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer comprises a michael acceptor-terminated urethane-containing prepolymer of formula (6a), a michael acceptor-terminated urethane-containing prepolymer of formula (6b), or a combination thereof:

R³⁰-C(＝O)-NH-R²⁰-NH-C(＝O)-[-R⁶⁰-C(＝O)-NH-R²⁰-NH-C(＝O)-]_w-R⁶⁰-C(＝O)-NH-R²⁰-NH-C(＝O)-R³⁰ (6a)

B{-V’-S-R⁵⁰-S-(CH₂)₂-O-R¹³-O-[-C(＝O)-NH-R²⁰-NH-C(＝O)-R⁶⁰-]_w-C(＝O)-NH-R²⁰-NH-C(＝O)-R³⁰}_z (6b)

wherein,

w is an integer from 1 to 100;

each R¹³Independently comprise C_2-10An alkanediyl group;

each R²⁰A core independently comprising a diisocyanate;

each R³⁰Independently comprise at least one terminal Michael acceptorA group;

each R⁵⁰A core independently comprising a sulfur-containing prepolymer;

each R⁶⁰Independently comprises a moiety having the structure of formula (7):

-O-R¹³-O-(CH₂)₂-S-R⁵⁰-S-(CH₂)₂-O-R¹³-O- (7)

b represents a z-valent polyfunctionalizing agent B (-V)_zThe core of (a), wherein,

z is an integer from 3 to 6; and

each V is a moiety comprising a terminal group reactive with a thiol; and

each-V' -results from the reaction of-V with a thiol.

In certain embodiments, each R is⁵⁰A polythioether derived from a polythioether and having the structure of formula (5):

-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n- (5)

wherein,

each R¹Independently selected from C_2-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-14Alkanecycloalkanediyl, C_5-8Heterocyclic alkanediyl, and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each R³Independently selected from hydrogen and methyl; and

each X is independently selected from-O-, -S-, and-NR-, wherein R is selected from hydrogen and methyl;

each R²Independently selected from C_1-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-14Alkanecycloalkanediyl, and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which s, q, R, R³And X is as for R¹As defined;

m is an integer from 0 to 50;

n is an integer from 1 to 60; and

p is an integer from 2 to 6.

In certain embodiments, the Michael acceptor-terminated urethane-containing prepolymer is derived from a thiol-terminated sulfur-containing adduct, a hydroxyvinyl ether, a diisocyanate, and 1, 3-bis (vinylsulfonyl) -2-propanol (HO-CH (-CH)₂-S(O)₂-CH＝CH₂)₂) And optionally a polyfunctionalizing agent. Thus, in certain embodiments, the michael acceptor-terminated urethane-containing prepolymer comprises a structure of formula (8a), formula (8b), or a combination thereof.

(CH₂＝CH-S(O)₂-CH₂-)₂CH-O-C(＝O)-NH-R²⁰-NH-C(＝O)-[-R⁶⁰-C(＝O)-NH-R²⁰-NH-C(＝O)-]_w-R⁶⁰-C(＝O)-NH-R²⁰-NH-C(＝O)-O-CH(-CH₂-S(O)₂-CH＝CH₂)₂ (8a)

B{-V’-S-R⁵⁰-S-(CH₂)₂-O-R¹³-O-[-C(＝O)-NH-R²⁰-NH-C(＝O)-R⁶⁰-]_w-C(＝O)-NH-R²⁰-NH-C(＝O)-O-CH(-CH₂-S(O)₂-CH＝CH₂)₂}_z (8b)

Wherein each R¹³Each R²⁰Each R⁵⁰Each R⁶⁰W, z, B, and each-V' -are as defined herein. In certain embodiments of formula (8a) and formula (8b), each R is⁵⁰Has the structure of formula (5).

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure comprise the reaction product of reactants comprising an isocyanate-terminated urethane-containing adduct and a compound comprising a group reactive with isocyanate and at least one michael acceptor group. In certain embodiments, the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure comprise the reaction product of reactants comprising an isocyanate-terminated urethane-containing adduct and comprising groups reactive with isocyanate; at least one michael acceptor group; and at least one metal ligand.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer is terminated with two or more michael acceptor groups. For example, each end of the linear prepolymer of formula (6a) may be terminated with one or more michael acceptor groups, and each arm of the multidentate prepolymer of formula (6b) may be terminated with one or more michael acceptor groups. In certain embodiments, the ends or arms of the prepolymer may be terminated with 2, 3, or 4 michael acceptor groups. For example, the arms of the tridentate prepolymer of formula (6b) may be terminated with one michael acceptor group, two michael acceptor groups, or three michael acceptor groups. The michael-acceptor terminated urethane-containing prepolymer may comprise a mixture of michael-acceptor terminated urethane-containing prepolymers having different numbers of terminal michael acceptor groups and may therefore be characterized by a non-integer michael acceptor functionality. Linear and multidentate michael acceptor-terminated urethane-containing prepolymers having different numbers of michael acceptor groups can be combined in different ratios to provide michael acceptor-terminated urethane-containing prepolymers characterized by a wide range of michael acceptor functionalities. Further, in certain embodiments, at least some of the ends or arms of the michael-acceptor terminated urethane-containing prepolymer may be terminated with a single michael acceptor group.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer has an isocyanate content of from 1% to 10%, from 2% to 6%, and in certain embodiments, from 3% to 5%.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer may be prepared by reacting an isocyanate-terminated urethane-containing adduct with a compound having at least one michael acceptor group, and optionally a metal ligand group, and a group reactive with isocyanate groups, such as a hydroxyl group. The reaction may be carried out in the presence of a suitable catalyst, such as dibutyltin dilaurate, at a suitable temperature, such as from 50 ℃ to 100 ℃ for a suitable time, such as from 0.5 hours to 5 hours.

In certain embodiments, the isocyanate-terminated urethane-containing adduct comprises an isocyanate-terminated urethane-containing polythioether adduct, an isocyanate-terminated urethane-containing polysulfide adduct, or a combination of any of the foregoing.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure are terminated with a moiety having a group reactive with isocyanate and at least one michael acceptor group. In certain embodiments, the capped moiety further comprises a metal ligand.

Groups reactive with isocyanate groups include hydroxyl groups, amine groups and thiol groups.

Michael acceptor groups are well known in the art. In certain embodiments, michael acceptor groups include activated alkenes, such as alkenyl groups adjacent to electron withdrawing groups such as alkenones, nitro groups, halogens, nitriles, carbonyl groups, or nitro groups. In certain embodiments, the michael acceptor group is selected from the group consisting of vinyl ketones, vinyl sulfones, quinones, enamines, ketimines, aldimines, and oxazolidines. In certain embodiments, each michael acceptor group may be the same, and in certain embodiments, at least some of the michael acceptor groups are different.

In certain embodiments, the michael acceptor group is a vinyl sulfone, such as divinyl sulfone.

In certain embodiments, each arm (arm) of the michael acceptor-terminated urethane-containing prepolymer may be terminated with 1 to 4 michael acceptor groups. In certain embodiments, each arm of the michael acceptor-terminated urethane-containing prepolymer comprises a terminal michael acceptor group. In certain embodiments, each arm of the michael acceptor-terminated urethane-containing prepolymer comprises two terminal michael acceptor groups.

In the formulae (6a) and (III)(6b) In certain embodiments of (1), each R is³⁰A bis (vinylsulfonyl) alkanol and having the structure of formula (9):

-O-CH(-R¹⁰-S(O)₂-CH＝CH₂)₂ (9)

wherein each R¹⁰Is C_1-3An alkanediyl group.

In certain embodiments, the compound comprising an isocyanate-reactive group and at least one michael acceptor group comprises a bis (vinylsulfonyl) alkanol.

In certain embodiments, the compound comprises a hydroxyl group and at least one michael acceptor group.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure are terminated with a compound having a group reactive with an isocyanate, at least one michael acceptor group, and at least one metal ligand.

In certain embodiments, the metal ligand is capable of coordinating to an aerospace surface.

In certain embodiments, the compound comprises a hydroxy group and two vinylsulfonyl groups.

A particularly suitable (covenient) compound, which includes two michael acceptor groups, a metal ligand and a hydroxyl group, is a bis (vinylsulfonyl) alkanol. The terminal vinylsulfonyl group is a michael acceptor, the bis (sulfonyl) group serves as a metal ligand, and the hydroxyl group can react with the isocyanate group of the isocyanate-terminated urethane-containing adduct.

In certain embodiments, the compound comprising a group reactive with isocyanate, at least one michael acceptor group and at least one metal ligand comprises a bis (vinylsulfonyl) alkanol, and in certain embodiments comprises 1, 3-bis (vinylsulfonyl) -2-propanol.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure are terminated in moieties that comprise at least one michael acceptor group and optionally at least one metal ligand, and are bonded to the isocyanate groups of the prepolymer via urethane linkages.

Thus, in certain embodiments, the michael acceptor/metal ligand-containing compound comprises a reactive hydroxyl group that is capable of reacting with the terminal isocyanate groups of the isocyanate-terminated urethane-containing adduct precursor.

Previous work by the present inventors has demonstrated that the incorporation of metal ligands into the backbone of sulfur-containing prepolymers and/or capping of the sulfur-containing prepolymers with metal ligands can improve the adhesion of coatings and sealants formed using prepolymers containing metal ligands to metal surfaces.

Bis (sulfonyl) alkanols represent a class of metal ligands that can be incorporated into the backbone of a polymer or form end groups (e.g., sulfur-containing prepolymers) to improve surface adhesion. Other metal ligands may also be incorporated into the polymer backbone to enhance surface adhesion. In certain embodiments, for example for aerospace sealant applications, the metal ligand may be selected from ligands capable of coordinating to aluminum, aluminum oxide, al (iii), anodized aluminum, titanium oxide, and/orOn the surface. The metal ligands may form bidentate, tridentate or higher (higher order) coordination complexes to the surface atoms.

Metal ligands and especially aluminum (III) metal ligands include hard (hard) Lewis bases such as-OH, -PO₄，-SO₄-COOH, -C ═ O and-NH₂A group capable of donating an electron to the empty orbital of the metal. Basic donor groups, which effectively form multidentate coordination complexes with aluminum (III), include aliphatic monohydroxy acid anions, catecholates (catholates), aromatic hydroxy acid anions, 3-hydroxy-4-pyridones, hydroxamates (hydroxamates), and 3-hydroxy-2-pyridones. The stable aluminum (III) complexes are those with multidentate ligands having negative oxygen electron donors. The metal ligand may form a multidentate complex, such as a bidentate complex or a tridentate complex, with the metal.

In certain embodiments, the metal ligand functional group is derived from a metal chelator selected from the group consisting of bis (sulfonyl) alkanols, hydroxypyridinones, and acetylacetonates.

Examples of aluminium, aluminium oxide and Al (III) chelating agents include 2, 3-dihydroxybenzoic acid, 5-nitrosalicylate, 3-hydroxy-4-pyridone, 3-hydroxy-2-pyridone, 2-2 '-dihydroxyazobenzene, 8-hydroxyquinoline, oxalate (oxylate), malonate, citrate, iminodiacetic acid, picolinic acid, maltol, kojic acid, N, N' -diacetic acid (EDTA), N- (2-hydroxy) ethylenediaminetriacetic acid (HEDTA), ethylenediamineN, N '-bis (2-hydroxyphenylacetic acid (EDDHA) and N, N' -bis (hydroxybenzyl) ethylenediaminetetraacetic acid (HBED), acetoacetate, acetylacetonate, catecholate, hydroxamates and quinones. Other aluminum and alumina chelating agents are disclosed in, for example, Yokel, Coordination Chemistry Reviews 2002, 228, 97-113; and Martell et al, correlation Chemistry Reviews 1996, 149, 311-328.

Examples of titanium or titanium oxide metal ligands include H₂O₂Acetylacetonate (CH)₂(COCH₃)₂) EDTA, trans-1, 2-cyclohexanediaminetetraacetic acid, glycol ether diamine tetraacetic acid (GEDTA, (CH)₂OCH₂CH₂N(CH₂COOH)₂)₂) Diethylene triamine pentaacetic acid (DTPA, HOOCH)₂N(CH₂CH₂N(CH₂COOH)₂)₂) Nitrilotriacetic acid (NTA, N (CH)₂COOH)₃) Salicylic acid, lactic acid, acetyl acetonate, triethanolamine, and combinations of any of the foregoing.

In certain embodiments, the metal ligand comprises at least two heteroatom groups, which are capable of coordinating to the aluminum (III) surface. In certain embodiments, the metal ligand comprises at least two heteroatom groups selected from: -OH, -PO₄，-P(O)₂-，-SO₄，-S(O)₂-，-COOH，-C＝O，-NH₂-NH-, and combinations of any of the foregoing.

In certain embodiments, the metal ligand functional group comprises a moiety selected from the group consisting of formula (10a), formula (10b), formula (10c), formula (10d), formula (10e), and a combination of any of the foregoing:

-X-(CH₂)_s-CH(-OH)- (10a)

-X-(CH₂)_s-CH(-OH)-(CH₂)_n-X- (10b)

-CH(-OH)-(CH₂)_s-X-(CH₂)_s-CH(-OH)- (10c)

-CH(-OH)-R⁵-CH(-OH)- (10d)

-C(O)-R⁵-C(O)- (10e)

wherein-X-is independently selected from-C (O) -or-S (O)₂-; each s is independently selected from 1,2 and 3; and R⁵Is C_1-3An alkanediyl group. In certain embodiments, each X is-c (o) -and each s is 1; and in certain embodiments, each X is-S (O)₂-and each s is 1.

In certain embodiments, the metal ligand comprises a bis (sulfonyl) alkanol, a hydroxypyridone, a quinone, an acetylacetonate, or a combination of any of the foregoing.

In certain embodiments, the isocyanate-terminated urethane-containing adduct comprises an isocyanate-terminated urethane-containing polythioether adduct, an isocyanate-terminated urethane-containing polysulfide adduct, or a combination thereof.

In certain embodiments, the isocyanate-terminated urethane-containing adduct comprises an isocyanate-terminated urethane-containing adduct of formula (11a), an isocyanate-terminated urethane-containing adduct of formula (11b), or a combination thereof:

O＝C＝N-R²⁰-NH-C(＝O)-[-R⁶⁰-C(＝O)-NH-R²⁰-NH-C(＝O)-]_w-R⁶⁰-C(＝O)-NH-R²⁰-N＝C＝O (11a)

B{-V’-S-R⁵⁰-S-(CH₂)₂-O-R¹³-O-[-C(＝O)-NH-R²⁰-NH-C(＝O)-R⁶⁰-]_w-C(＝O)-NH-R²⁰-N＝C＝O}_z (11b)

wherein,

w is an integer from 1 to 100;

each R¹³Independently comprise C_2-10An alkanediyl group;

each R²⁰A core independently comprising a diisocyanate;

each R³⁰Independently comprises at least one terminal michael acceptor group;

each R⁵⁰A core independently comprising a sulfur-containing prepolymer;

-O-R¹³-O-(CH₂)₂-S-R⁵⁰-S-(CH₂)₂-O-R¹³-O- (7)

z is an integer from 3 to 6; and

each V is a moiety comprising a terminal group reactive with a thiol group; and

each-V' -results from the reaction of-V with a thiol.

In certain embodiments of formulas (11a) and (11b), each R⁵⁰Derived from a polythioether. For example, in certain embodiments, each R is⁵⁰Having the structure of formula (5):

-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n- (5)

wherein,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each one of which isR³Independently selected from hydrogen and methyl; and

m is an integer from 0 to 50;

n is an integer from 1 to 60; and

p is an integer from 2 to 6.

In certain embodiments of formulae (11a) and (11b), w is an integer from 2 to 50, and in certain embodiments from 2 to 20.

In certain embodiments, the isocyanate-terminated urethane-containing adduct comprises the reaction product of reactants comprising a hydroxyl-terminated sulfur-containing adduct and a diisocyanate.

In certain embodiments, the hydroxyl-terminated sulfur-containing adduct and the diisocyanate are reacted in a molar ratio such that the isocyanate-terminated urethane-containing adduct comprises alternating sulfur-containing moieties and units of diisocyanate. In certain embodiments, the isocyanate-terminated urethane-containing adduct comprises the reaction product of reactants comprising a hydroxyl-terminated3.1E and diisocyanates such as cycloaliphatic diisocyanates.

In certain embodiments, the isocyanate-terminated urethane-containing prepolymer has an isocyanate content of from 1% to 10%, from 2% to 6%, and in certain embodiments, from 3% to 5%.

The isocyanate-terminated urethane-containing adduct may be synthesized, for example, by reacting a diisocyanate with a suitably terminated sulfur-containing adduct, such as, for example, a hydroxyl-terminated sulfur-containing adduct, in the presence of a tin catalyst, such as dibutyltin dilaurate, at a suitable temperature, for example, from 50 ℃ to 100 ℃ for a suitable time, for example, from 1 hour to 4 hours. One skilled in the art can determine appropriate reaction conditions.

In certain embodiments, the sulfur-containing adducts provided by the present disclosure comprise terminal hydroxyl groups that are reactive with isocyanate groups and can be reacted directly with a polyisocyanate, such as a diisocyanate, to provide isocyanate-terminated urethane-containing adducts that are useful in forming the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure.

In certain embodiments, the sulfur-containing adduct may be functionalized to provide groups sufficient to react with isocyanate groups. For example, in certain embodiments, the thiol-terminated sulfur-containing adduct provides suitable precursors to form the michael acceptor-terminated urethane-containing prepolymer of the present disclosure. To make the thiol-terminated sulfur-containing prepolymer reactive with isocyanate groups, the thiol-terminated sulfur-containing prepolymer may be functionalized with hydroxyl groups. In certain embodiments, the thiol-terminated sulfur-containing adduct may be reacted with a compound having groups reactive with alkenyl and hydroxyl groups. Examples of such compounds include hydroxy vinyl ethers.

In certain embodiments, the hydroxyl-terminated sulfur-containing adduct comprises a hydroxyl-terminated polysulfide adduct, such as a hydroxyl-terminated polysulfide adduct of formula (12a), a hydroxyl-terminated polysulfide adduct of formula (12b), or a combination thereof.

R⁶-S-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-R⁶ (12a)

{R⁶-S-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-V’-}_zB (12b)

Wherein R is¹，R²M, n, and p are as defined herein, and each R⁶Is a moiety containing a terminal hydroxyl group.

In certain embodiments, each R is⁶A hydroxy vinyl ether and having the structure of formula (13):

-CH₂-CH₂-O-R¹³-OH (13)

wherein R is¹³Is C_2-10An alkanediyl group. In certain embodiments R¹³Is- (CH)₂)₄-。

The isocyanate-terminated urethane-containing adduct may be prepared by reacting a polyisocyanate with a sulfur-containing adduct comprising terminal groups reactive with isocyanate groups, such as terminal hydroxyl groups. The polyisocyanate may be difunctional, n-functional, where n is an integer from 3 to 6, or a combination of any of the foregoing. In certain embodiments, the polyisocyanate is difunctional and is referred to as a diisocyanate. The diisocyanate may be aliphatic, cycloaliphatic or aromatic.

Examples of suitable aliphatic diisocyanates include 1, 6-hexamethylene diisocyanate, 1, 5-diisocyanato-2-methylpentane, methyl 2, 6-diisocyanatohexanoate, bis (isocyanatomethyl) cyclohexane, 1, 3-bis (isocyanatomethyl) cyclohexane, 2,2, 4-trimethylhexane 1, 6-diisocyanate, 2,4, 4-trimethylhexane 1, 6-diisocyanate, 2, 5(6) -bis (isocyanatomethyl) cyclo [2.2.1 ].]Heptane, 1,3, 3-trimethyl-1- (isocyanatomethyl) -5-isocyanatocyclohexane, 1, 8-diisocyanato-2, 4-dimethyloctane, octahydro-4, 7-methano-1H-indenedimethyldiisocyanate and 1, 1' -methylenebis (4-isocyanatocyclohexane), and 4, 4-methylenedicyclohexyldiisocyanate) (H₁₂MDI). Examples of suitable aromatic diisocyanates include 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 2, 6-toluene diisocyanate (2, 6-TDI), 2, 4-toluene diisocyanate (2, 4-TDI), a blend of 2, 4-TDI and 2, 6-TDI, 1, 5-diisocyanatonaphthalene, diphenyloxy 4,4 '-diisocyanate, 4, 4' -methylenediphenyl diisocyanate (4, 4-MDI), 2,4 '-methylenediphenyl diisocyanate (2, 4-MDI), 2,2' -diisocyanatodiphenylmethane (2, 2-MDI), diphenylmethanesAlkanediisocyanate (MDI), 3,3 '-dimethyl-4, 4' -biphenylene isocyanate, 3,3 '-dimethoxy-4, 4' -biphenylene diisocyanate, 1- [ (2, 4-diisocyanatophenyl) methyl]-3-isocyanato-2-methylbenzene, and 2,4, 6-triisopropyl-m-phenylene diisocyanate.

Examples of suitable cycloaliphatic diisocyanates from which the diisocyanate may be selected include isophorone diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, bis (isocyanatomethyl) cyclohexane, bis (isocyanatocyclohexyl) methane, bis (isocyanatocyclohexyl) -2, 2-propane, bis (isocyanatocyclohexyl) -1, 2-ethane, 2-isocyanatomethyl-3- (3-isocyanatopropyl) -5-isocyanatomethyl-bicyclo [2.2.1] -heptane, 2-isocyanatomethyl-3- (3-isocyanatopropyl) -6-isocyanatomethyl-bicyclo [2.2.1] -heptane, 2-isocyanatomethyl-2- (3-isocyanatopropyl) -5-isocyanatomethyl-bicyclo [2.2.1] -heptane 2.2.1] -heptane, 2-isocyanatomethyl-2- (3-isocyanatopropyl) -6-isocyanatomethyl-bicyclo [2.2.1] -heptane, 2-isocyanatomethyl-3- (3-isocyanatopropyl) -6- (2-isocyanatoethyl) -bicyclo [2.2.1] -heptane, 2-isocyanatomethyl-2- (3-isocyanatopropyl) -5- (2-isocyanatoethyl) -bicyclo [2.2.1] -heptane and 2-isocyanatomethyl-2- (3-isocyanatopropyl) -6- (2-isocyanatoethyl) -bicyclo [2.2.1] -heptane.

Examples of suitable aromatic diisocyanates, wherein the isocyanate groups are not directly bonded to the aromatic ring, include, but are not limited to, bis (isocyanatoethyl) benzene, α, α, α ', α' -tetramethylxylene diisocyanate, 1, 3-bis (1-isocyanato-1-methylethyl) benzene, bis (isocyanatobutyl) benzene, bis (isocyanatomethyl) naphthalene, bis (isocyanatomethyl) diphenyl ether, bis (isocyanatoethyl) phthalate, and 2, 5-bis (isocyanatomethyl) furan. Aromatic diisocyanates having an isocyanate group directly bonded to an aromatic ring include phenylene diisocyanate, ethylphenylene diisocyanate, isopropylphenylene diisocyanate, dimethylphenylene diisocyanate, diethylphenylene diisocyanate, diisopropylphenylene diisocyanate, naphthalene diisocyanate, methylnaphthalene diisocyanate, biphenyl diisocyanate, 4, 4' -diphenylmethane diisocyanate, bis (3-methyl-4-isocyanatophenyl) methane, bis (isocyanatophenyl) ethylene, 3, 3' -dimethoxy-biphenyl-4, 4' -diisocyanate, diphenyl ether diisocyanate, bis (isocyanatophenyl ether) ethylene glycol, bis (isocyanatophenyl ether) -1, 3-propylene glycol, benzophenone diisocyanate, carbazole diisocyanate, ethylcarbazole diisocyanate, dichlorocarbazole diisocyanate, 4, 4' -diphenylmethane diisocyanate, p-phenylene diisocyanate, 2, 4-toluene diisocyanate and 2, 6-toluene diisocyanate.

Other examples of suitable diisocyanates include 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 2, 6-toluene diisocyanate (2, 6-TDI), 2, 4-toluene diisocyanate (2, 4-TDI), a blend of 2, 4-TDI and 2, 6-TDI, 1, 5-diisocyanatonaphthalene, diphenyloxy 4,4 '-diisocyanate, 4, 4' -methylenediphenyl diisocyanate (4, 4-MDI), 2,4 '-methylenediphenyl diisocyanate (2, 4-MDI), 2,2' -diisocyanatodiphenylmethane (2, 2-MDI), diphenylmethane diisocyanate (MDI), 3,3 '-dimethyl-4, 4' -biphenylene isocyanate, 3,3 '-dimethoxy-4, 4' -biphenylene diisocyanate, 1- [ (2, 4-diisocyanatophenyl) methyl]3-isocyanato-2-methylbenzene, 2,4, 6-triisopropyl-m-phenylene diisocyanate, 4, 4-methylenedicyclohexyl diisocyanate (H)₁₂MDI), and combinations of any of the foregoing.

Further examples of suitable aromatic diisocyanates include 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 2, 6-toluene diisocyanate (2, 6-TDI), 2, 4-toluene diisocyanate (2, 4-TDI), a blend of 2, 4-TDI and 2, 6-TDI, 1, 5-diisocyanatonaphthalene, diphenyloxy 4,4 '-diisocyanate, 4, 4' -methylenediphenyl diisocyanate (4, 4-MDI), 2,4 '-methylenediphenyl diisocyanate (2, 4-MDI), 2,2' -diisocyanatodiphenylmethane (2, 2-MDI), diphenylmethane diisocyanate (MDI), 3,3 '-dimethyl-4, 4' -biphenylene isocyanate, 3,3 '-dimethoxy-4, 4' -biphenylene diisocyanate, 1- [ (2, 4-diisocyanatophenyl) methyl ] -3-isocyanato-2-methylbenzene and 2,4, 6-triisopropyl-m-phenylene diisocyanate.

The isocyanate-terminated urethane-containing adduct can be prepared, for example, by reacting a hydroxyl-terminated sulfur-containing adduct (e.g., a hydroxyl-terminated polythioether of formula (12a) and formula (12 b)) with a compound having terminal isocyanate groups and groups reactive with the terminal hydroxyl groups of the polythioether of formula (12a) and formula (12b) (e.g., a diisocyanate).

In certain embodiments, the isocyanate-terminated urethane-containing polythioether adduct can be prepared, for example, as follows: by reacting a hydroxyl-terminated polythioether adduct of formula (12a) or formula (12b) with a diisocyanate such as TDI, Isonate^TM143L (polycarbodiimide-modified diphenylmethane diisocyanate),n3400(1, 3-diazidine-2, 4-dione, 1, 3-bis (6-isocyanatohexyl) -), IDPI (isophorone diisocyanate) orW (H12MDI), optionally in the presence of a catalyst such as dibutyltin dilaurate, in an organic solvent such as benzoyl chloride, at a temperature of about 70 ℃ to about 80 ℃ to provide the corresponding isocyanate-terminated urethane-containing polythioether adducts of formulae (6a), (6b), (8a) and (8 b).

In certain embodiments, the moiety-C (═ O) -NH-R²⁰-NH-C (═ O) -a diisocyanate obtainable from formula (14):

O＝C＝N-R²⁰-N＝C＝O (14)

in certain embodiments, the hydroxyl-terminated sulfur-containing adduct comprises the reaction product of reactants comprising a thiol-terminated sulfur-containing adduct and a hydroxy vinyl ether.

In certain embodiments, the thiol-terminated sulfur-containing adduct comprises a thiol-terminated polythioether adduct, a thiol-terminated polysulfide adduct, or a combination thereof.

In certain embodiments, the thiol-terminated sulfur-containing adduct comprises a thiol-terminated polythioether adduct. Examples of thiol-functional polythioether adducts are disclosed in, for example, U.S. Pat. No.6,172,179. In certain embodiments, the thiol-functional polysulfide adduct comprisesP3.1E, available from PRC-Desoto International Inc., Sylmar, Calif.

In certain embodiments, the thiol-terminated sulfur-containing adduct comprises a thiol-terminated polythioether selected from a thiol-terminated polythioether adduct of formula (15a), a thiol-terminated polythioether adduct of formula (15b), and a combination thereof:

HS-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-SH (15a)

{HS-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-V’-}_zB (15b)

wherein,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each R³Independently selected from hydrogen and methyl; and

m is an integer from 0 to 50;

n is an integer from 1 to 60;

p is an integer from 2 to 6;

z is an integer from 3 to 6; and

each V is a moiety comprising a terminal group reactive with a thiol; and

each-V' -results from the reaction of-V with a thiol.

In certain embodiments, of formula (15a) and in formula (15b), R¹Is- [ (-CH)₂-)_p-X-]_q-(CH₂)_r-, where p is 2, X is-O-, q is 2, R is 2, R is²Is ethanediyl, m is 2, and n is 9.

In certain embodiments of formula (15a) and formula (15b), R¹Is selected from C_2-6Alkanediyl and- [ - (CHR)³)_s-X-]_q-(CHR³)_r-。

In certain embodiments of formula (15a) and formula (15b), R¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, and in certain embodiments X is-O-and in certain embodiments X is-S-.

In certain embodiments of formula (15a) and formula (15b), wherein R is¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, p is 2, r is 2, q is 1, and X is-S-; in certain embodiments, wherein p is 2, q is 2, r is 2, and X is-O-; and in certain embodiments, p is 2, r is 2, q is 1, and X is-O-.

In certain embodiments of formulae (15a) and (15b), wherein R¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, each R³Is hydrogen, and in certain embodiments, at least one R³Is methyl.

In certain embodiments of formula (15a) and formula (15b), each R is¹Are the same, and in certain embodiments, at least one R¹Is different.

A variety of methods can be used to prepare the thiol-terminated polythioethers of formula (15a) and formula (15 b). Examples of suitable thiol-terminated polythioethers, and methods for their production, are described in U.S. Pat. No.6,172,179, column 2, line 29 to column 4, line 22; column 6, line 39 to column 10, line 50; and column 11, line 65 through column 12, line 22, the referenced sections of which are incorporated by reference. Such thiol-terminated polythioethers may be difunctional, i.e., linear polymers having two thiol terminal groups, or polyfunctional, i.e., branched polymers having three or more thiol terminal groups. Suitable thiol-terminated polythioethers are commercially available, for example asP3.1E are commercially available from PRC-Desoto International Inc., Sylmar, Calif.

In certain embodiments, the thiol-terminated sulfur-containing polymer comprises a polythioether. The sulfur-containing polymer can comprise a mixture of different polythioethers and the polythioethers can have the same or different functionalities. In certain embodiments, the sulfur-containing polymer has an average functionality of from 2 to 6, 2 to 4, 2 to 3, and in certain embodiments, from 2.05 to 2.5. For example, the sulfur-containing polymer can be selected from difunctional sulfur-containing polymers, trifunctional sulfur-containing polymers, and combinations thereof.

In certain embodiments, thiol-terminated polythioethers can be prepared by reacting a polythiol with a diene (such as divinyl ether), and the respective amounts of reactants used to prepare the polythioether are selected to produce terminal thiol groups. Thus, in some cases, (n or > n, such as n +1) moles of a polythiol, such as a dithiol or a mixture of at least two different dithiols and about 0.05 moles to 1 mole, such as 0.1 moles to 0.8 moles of a thiol-terminated polyfunctionalizing agent may be reacted with (n) moles of a diene (such as divinyl ether), or a mixture of at least two different dienes (such as divinyl ether). In certain embodiments, the thiol-terminated polyfunctionalizing agent is present in the reaction mixture in an amount sufficient to provide a thiol-terminated polythioether having an average functionality of from 2.05 to 3, such as from 2.1 to 2.8.

The reaction for making the thiol-terminated polythioether can be catalyzed by a free radical catalyst. Suitable free radical catalysts include azo compounds, such as azodinitrile compounds, for example, azo (di) isobutyronitrile (AIBN); organic peroxides such as benzoyl peroxide and t-butyl peroxide; and inorganic peroxides such as hydrogen peroxide. The reaction can also be carried out by irradiation with ultraviolet radiation (with or without a radical initiator/photosensitizer). Ion-catalyzed processes using inorganic or organic bases such as triethylamine can also be used.

Suitable thiol-terminated polythioethers can be produced by reacting a divinyl ether or a mixture of divinyl ethers with an excess of a dithiol or a mixture of dithiols.

Thus, in certain embodiments, a thiol-terminated polythioether comprises the reaction product of reactants comprising:

(a) a dithiol of formula (16):

HS-R¹-SH (16)

wherein,

R¹is selected from C_2-6Alkanediyl, C_6-8Cycloalkanediyl group, C_6-10Alkanecycloalkanediyl, C_5-8Heterocycloalkyl diyl, and- [ - (CHR)³)_s-X-]_q-(CHR³)_r-; wherein,

each R³Independently selected from hydrogen and methyl;

each X is independently selected from-O-, -S-, -NH-, and-NR-, wherein R is selected from hydrogen and methyl;

s is an integer from 2 to 6;

q is an integer of 1 to 5; and

r is an integer from 2 to 10; and

(b) a divinyl ether of formula (17):

CH₂＝CH-O-[-R²-O-]_m-CH＝CH₂ (17)

wherein,

each R²Independently selected from C_1-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-14Alkanecycloalkanediyl, and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which s, q, R, R³And X is as defined above;

m is an integer from 0 to 50;

n is an integer from 1 to 60; and

p is an integer from 2 to 6.

And, in certain embodiments, the reactants can comprise (c) a polyfunctional compound such as polyfunctional compound B (-V)_zWherein B, -V, and z are as defined herein.

In certain embodiments, dithiols suitable for use in preparing thiol-terminated polythioethers include those having formula (16), other dithiols disclosed herein, or any combination of dithiols disclosed herein. In certain embodiments, the dithiol has the structure of formula (16):

HS-R¹-SH (16)

wherein,

each R³Independently selected from hydrogen and methyl;

s is an integer from 2 to 6;

q is an integer of 1 to 5; and

r is an integer from 2 to 10.

In certain embodiments of the dithiols of formula (16), R¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-。

In certain embodiments of the compounds of formula (16), X is selected from-O-and-S-, and thus- [ - (CHR) in formula (16)³)_s-X-]_q-(CHR³)_r-is- [ (-CHR)³-)_s-O-]_q-(CHR³)_r-or- [ (-CHR)³ ₂-)_s-S-]_q-(CHR³)_r-. In certain embodiments, p and r are equal, such as where p and r are both two.

In certain embodiments of the dithiols of formula (16), R¹Is selected from C_2-6Alkanediyl and- [ - (CHR)³)_s-X-]_q-(CHR³)_r-。

In certain embodiments of the dithiols of formula (16), R¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, and in certain embodiments X is-O-, and in certain embodiments X is-S-.

In certain embodiments wherein R¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, S is 2, r is 2, q is 1, and X is-S-; in certain embodiments, wherein s is 2, q is 2, r is 2, and X is-O-; and in certain embodiments, s is 2, r is 2, q is 1, and X is-O-.

In certain embodiments, wherein R is¹Is- [ - (CHR)³)_s-X-]_q-(CHR³)_r-, each R³Is hydrogen, and in certain embodiments, at least one R³Is methyl.

In certain embodiments of formula (16), each R¹Derived from dimercaptodioxaoctane (DMDO) and, in certain embodiments, each R¹From dimercaptodiethylsulfide (DMDS).

In certain embodiments of formula (16), each m is independently an integer from 1 to 3. In certain embodiments, each m is the same and is 1,2, and in certain embodiments, 3.

In certain embodiments of formula (16), n is an integer from 1 to 30, an integer from 1 to 20, an integer from 1 to 10, and in certain embodiments, an integer from 1 to 5. Furthermore, in certain embodiments, n can be any integer from 1 to 60.

In certain embodiments of formula (16), each p is independently selected from 2, 3, 4, 5, and 6. In certain embodiments, each p is the same and is 2, 3, 4, 5, or 6.

Examples of suitable dithiols include, for example, 1, 2-ethanedithiol, 1, 2-propanedithiol, 1, 3-butanedithiol, 1, 4-butanedithiol, 2, 3-butanedithiol, 1, 3-pentanedithiol, 1, 5-pentanedithiol, 1, 6-hexanedithiol, 1, 3-dimercapto-3-methylbutane, dipentene dithiol, ethylcyclohexyl dithiol (ECHDT), dimercaptodiethylsulfide, methyl-substituted dimercaptodiethylsulfide, dimethyl-substituted dimercaptodiethylsulfide, dimercaptodioxaoctane, 1, 5-dimercapto-3-oxapentane, and combinations of any of the foregoing. The polythiol can have a structure selected from the group consisting of lower (e.g., C)_1-6) Alkyl groups, lower alkoxy groups, and one or more pendant hydroxyl groups. Suitable alkyl side groups include, for example, C_1-6Linear alkyl radical, C_3-6Branched alkyl, cyclopentyl and cyclohexyl.

Other examples of suitable dithiols include dimercaptodiethylsulfide (DMDS) (in formula (16), R is¹Is- [ (-CH)₂-)_s-X-]_q-(CH₂)_r-, where S is 2, r is 2, q is 1, and X is-S-); dimercaptodioxaoctane (DMDO) (in formula (16), R¹Is- [ (-CH)₂-)_s-X-]_q-(CH₂)_r-, where s is 2, q is 2, r is 2, and X is-O-); and 1, 5-dimercapto-3-oxapentane (in formula (16), R¹Is- [ (-CH)₂-)_s-X-]_q-(CH₂)_r-, where s is 2, r is 2, q is 1, and X is-O-. It is also possible to use dithiols which include two heteroatoms in the carbon backbone and pendant alkyl groups, such as methyl groups. Such compounds include, for example, methyl-substituted DMDS, e.g. HS-CH₂CH(CH₃)-S-CH₂CH₂-SH，HS-CH(CH₃)CH₂-S-CH₂CH₂-SH and dimethylSubstituted DMDS, e.g. HS-CH₂CH(CH₃)-S-CHCH₃CH₂-SH and HS-CH (CH)₃)CH₂-S-CH₂CH(CH₃)-SH。

Suitable divinyl ethers for preparing polythioethers include, for example, divinyl ethers of formula (17):

CH₂＝CH-O-(-R²-O-)_m-CH＝CH₂ (17)

wherein R in the formula (17)²Is selected from C_2-6N-alkanediyl radical, C_3-6Branched alkanediyl radical, C_6-8Cycloalkanediyl group, C_6-10Alkanecycloalkanediyl group, and- [ (-CH)₂-)_s-O-]_q-(-CH₂-)_r-, where s is an integer from 2 to 6, q is an integer from 1 to 5, and r is an integer from 2 to 10. In certain embodiments of the divinyl ethers of formula (17), R²Is C_2-6N-alkanediyl radical, C_3-6Branched alkanediyl radical, C_6-8Cycloalkanediyl group, C_6-10Alkanecycloalkanediyl groups, and in certain embodiments, - [ (-CH)₂-)_s-O-]_q-(-CH₂-)_r-。

Suitable divinyl ethers include, for example, compounds having at least one oxyalkyldiyl group, such as 1 to 4 oxyalkyldiyl groups, i.e. compounds wherein m in formula (17) is an integer from 1 to 4. In certain embodiments, m in formula (17) is an integer from 2 to 4. It is also possible to use commercially available divinyl ether mixtures characterized by non-integral average numbers of oxyalkyldiyl units per molecule. Thus, in formula (17) m may also be a rational number in the range of 0-10.0, such as 1.0-10.0, 1.0-4.0, or 2.0-4.0.

Examples of suitable vinyl ethers include divinyl ether, ethylene glycol divinyl ether (EG-DVE) (R in formula (17))²Is ethanediyl and m is 1), butanediol divinyl ether (BD-DVE) (in formula (17) R²Is butanediyl and m is 1), hexanediol divinyl ether (HD-DVE) (R in the formula (17)²Hexanediyl and m is 1), diethylene glycol divinyl ether (DEG-DVE) (R in formula (17)²Is ethanediyl and m is 2), triethylene glycol divinyl ether (R in the formula (17)²Is ethanediyl and m is 3), tetraethyleneglycol divinyl ether (R in the formula (17)²Is ethanediyl and m is 4), cyclohexanedimethanol divinyl ether, polytetrahydrofuranyl divinyl ether; trivinyl ether monomers such as trimethylolpropane trivinyl ether; tetrafunctional ether monomers such as pentaerythritol tetravinyl ether; and combinations of two or more such polyvinyl ether monomers. The polyvinyl ether may have one or more pendant groups selected from alkyl groups, hydroxyl groups, alkoxy groups, and amine groups.

In certain embodiments, wherein R in formula (17)²Is C_3-6Branched alkanediyl divinyl ethers may be prepared by reacting a polyol with acetylene. Examples of divinyl ethers of this type include those in which R is in formula (17)²Is an alkyl-substituted methanediyl group such as-CH (-CH)₃) A compound of formula (17) for which R is²Is ethanediyl and m is 3 or alkyl-substituted ethanediyl.

Other useful divinyl ethers include those wherein R is in formula (17)²Compounds that are polytetrahydrofuranyl (poly-THF) or polyoxyalkanediyl, such as those having an average of about 3 monomer units.

Two or more types of the polyvinyl ether monomer of formula (17) may be used. Thus, in certain embodiments, two dithiols of formula (16) and one polyvinyl ether monomer of formula (17), one dithiol of formula (16) and two polyvinyl ether monomers of formula (17), two dithiols of formula (16) and two divinyl ether monomers of formula (17), and more than two compounds of one or both of formula (16) and formula (17) can be used to produce a variety of thiol-terminated polythioethers.

In certain embodiments, the polyvinyl ether monomer comprises from 20 to less than 50 mole percent, and in certain embodiments from 30 to less than 50 mole percent, of the reactants used to prepare the thiol-terminated polythioether.

In certain embodiments provided by the present disclosure, the relative amounts of dithiol and divinyl ether are selected to produce a polythioether having terminal thiol groups. Thus, a dithiol of formula (16), or a mixture of at least two different dithiols of formula (16), may be reacted with a divinyl ether of formula (17), or a mixture of at least two different divinyl ethers of formula (17), in relative amounts such that the molar ratio of thiol groups to alkenyl groups is greater than 1: 1, such as 1.1-2.0: 1.0.

the reaction between dithiols and divinyl ethers and/or polythiols and polyvinyl ethers may be catalysed by free radical catalysts. Suitable free radical catalysts include, for example, azo compounds, such as azodinitriles, for example, azo (di) isobutyronitrile (AIBN); organic peroxides such as benzoyl peroxide and t-butyl peroxide; and inorganic peroxides such as hydrogen peroxide. The catalyst may be a free radical catalyst, an ionic catalyst or ultraviolet radiation. In certain embodiments, the catalyst does not contain an acidic or basic compound and does not produce an acidic or basic compound after decomposition. Examples of the radical catalyst include azo type catalysts such as(Du Pont)，(Du Pont)，(Du Pont)，(Wako Specialty Chemicals) and(Wako Specialty Chemicals). Examples of other free radical catalysts are alkyl peroxides, such as tert-butyl peroxide. The reaction may also be carried out by irradiation with ultraviolet light (with or without cationic photoinitiating moieties).

The thiol-terminated polythioethers provided by the present disclosure can be prepared as follows: the at least one dithiol of formula (16) and the at least one divinyl ether of formula (17) are combined, followed by addition of a suitable catalyst, and the reaction is carried out at a temperature of 30 ℃ to 120 ℃, such as 70 ℃ to 90 ℃, for a period of 2 hours to 24 hours, such as 2 hours to 6 hours.

As disclosed herein, the thiol-terminated polythioether can comprise a multifunctional polythioether, i.e., can have an average functionality of greater than 2.0. Suitable polyfunctional thiol-terminated polythioethers include, for example, those having the structure of formula (18):

{HS-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-V’-}_zB(18)

wherein z has an average value greater than 2.0, and in certain embodiments has a value from 2 to 3, a value from 2 to 4, a value from 3 to 6, and in certain embodiments an integer from 3 to 6.

Polyfunctionalizing agents suitable for use in preparing such polyfunctional thiol-terminated polymers include trifunctionalizing agents, i.e., compounds wherein z is 3. Suitable trifunctionalizing agents include, for example, Triallylcyanurate (TAC), 1,2, 3-propanetrithiol, isocyanurate-containing trithiol, and combinations thereof, as disclosed in U.S. publication No. 2010/0010133 paragraphs [0102] - [0105], the referenced portions of which are incorporated by reference, and isocyanurates such as, for example, those disclosed in U.S. application publication No. 2011/0319559, which is incorporated by reference in its entirety. Other useful polyfunctionalizing agents include trimethylolpropane trivinyl ether, and the compounds described in U.S. Pat. Nos. 4366307; 4609762, respectively; and 5225472, each of which is incorporated herein by reference in its entirety. Mixtures of polyfunctionalizing agents may also be used. Thus, the polythioethers provided by the present disclosure can have a wide range of average functionalities. For example, the trifunctional agent may provide an average functionality of from 2.05 to 3.0, such as from 2.1 to 2.6. A broader range of average functionality can be achieved by using tetrafunctional or higher functionality polyfunctionalizing agents. The functionality will also depend on factors such as stoichiometry, as will be understood by those skilled in the art.

In certain embodiments, the hydroxyl-terminated sulfur-containing adduct may be formed by reacting a thiol-terminated sulfur-containing adduct with a hydroxy vinyl ether.

In certain embodiments, hydroxyvinyl ethers may be used to functionalize thiol-terminated sulfur-containing adducts with groups reactive with isocyanate groups. In certain embodiments, the hydroxy-functional vinyl ether has the structure of formula (19)

CH₂＝CH-O-(CH₂)_t-OH (19)

Wherein t is an integer from 2 to 10.

Examples of suitable hydroxy-functional vinyl ethers that can be used to react with the thiol-terminated sulfur-containing prepolymer include 1, 4-cyclohexanedimethylol monovinyl ether, 1-methyl-3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, and combinations of any of the foregoing. In certain embodiments, the hydroxy-functional vinyl ether is 4-hydroxybutyl vinyl ether.

In certain embodiments, the Michael acceptor-terminated urethane-containing prepolymer may be prepared in a three-step reaction. The reaction sequence involves providing an isocyanate-terminated urethane-containing adduct, followed by capping the terminal isocyanate groups with a multifunctional michael acceptor. One skilled in the art will appreciate that other chemistries can be used to synthesize the disclosed michael acceptor-terminated urethane-containing prepolymers. For example, rather than using a thiol-terminated sulfur-containing prepolymer, an alkenyl-terminated sulfur-containing prepolymer can be used and linked to the polyisocyanate via a diamine. Accordingly, it would be desirable to provide synthetic methods, precursors, and intermediates such that the michael acceptor-terminated urethane-containing prepolymers comprise urethane-containing and sulfur-containing backbones having urethane groups that are terminated with multifunctional michael acceptors.

In a first step, the thiol-terminated sulfur-containing adduct can be reacted with a hydroxy vinyl ether to provide a hydroxy-terminated sulfur-containing adduct. The reaction may be carried out at elevated temperature in the presence of a free radical initiator.

In the second step, the hydroxyl-terminated sulfur-containing adduct may be reacted with a polyisocyanate, such as a diisocyanate, to provide an isocyanate-terminated urethane-containing adduct. The reaction may be carried out at elevated temperature in the presence of a tin catalyst.

In a third step, the isocyanate-terminated urethane-containing adduct may be reacted with a multifunctional michael acceptor to provide a multifunctional michael acceptor-terminated urethane-containing prepolymer of the present disclosure. The reaction may be carried out at elevated temperature in the presence of a tin catalyst.

An example of a suitable reaction sequence is provided below:

wherein R is¹³，R²⁰，R³⁰，R⁵⁰And R⁶⁰Are defined herein. An example of a reaction sequence is shown in figure 1. The reaction sequence shown above and in FIG. 1 begins with the reaction of the dithiol. In certain embodiments, the reaction can be initiated with a polythiol, such as a trithiol, or with a mixture of polythiols, such as a combination of a dithiol and a trithiol.

The michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure may be included in the composition. The composition containing the michael acceptor-terminated urethane-containing prepolymer may include one or more additives including one or more curatives. In certain embodiments, the composition includes a latent curing agent that can be activated and/or released to initiate a curing reaction prior to use.

The michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure include reactive michael acceptor groups and thus the curable compositions may employ michael acceptor curing chemistry.

Michael addition chemistry can be used in various ways to provide curable compositions. For example, the curable compositions provided by the present disclosure may comprise a michael acceptor-terminated urethane-containing prepolymer provided by the present disclosure and a curing agent comprising at least two terminal groups reactive with michael acceptor groups. In certain compositions, the sulfur-containing compound comprises a sulfur-containing prepolymer such as a polythioether prepolymer comprising terminal groups reactive with michael acceptor groups, in certain embodiments the sulfur-containing prepolymer comprises a polythioether prepolymer, and in certain embodiments, a thiol-terminated polythioether adduct.

In certain embodiments, the composition comprises a michael acceptor-terminated urethane-containing prepolymer provided by the present disclosure and a curing agent. In certain embodiments, the curing agent may be a sulfur-containing compound comprising terminal groups reactive with michael acceptor groups, a sulfur-containing prepolymer, or a combination thereof. In certain embodiments, the curing agent comprises a terminal thiol group reactive with michael acceptor groups.

In certain compositions, the sulfur-containing prepolymers used as curing agents include any of the thiol-terminated sulfur-containing adducts disclosed herein. In certain embodiments, the thiol-terminated sulfur-containing adduct comprises a polysulfide prepolymer, and in certain embodiments the thiol-terminated polysulfide adduct has an average functionality of from 2 to 3, 2.2 to 2.8, and in certain embodiments, from 2.4 to 2.6. In certain embodiments, the thiol-terminated sulfur-containing adduct has an average functionality of 2.

In certain embodiments, the curing agent comprises a thiol-terminated sulfur-containing adduct, including any of the thiol-terminated adducts disclosed herein. In certain embodiments, the michael-acceptor urethane-containing prepolymer comprises a prepolymer of formula (6a), formula (6b), formula (8a), formula (8b), or a combination of any of the foregoing, and the thiol-terminated sulfur-containing adduct curing agent comprises a polythioether of formula (15a), formula (15b), or a combination thereof. In certain embodiments, the thiol-terminated sulfur-containing prepolymer curative comprises3.1E。

In such compositions, the michael acceptor groups of the michael acceptor urethane-containing prepolymer are reactive with the terminal groups of the sulfur-containing curative. For example, the michael acceptor group may be an activated alkenyl group, e.g., a michael acceptor group, and the curing agent comprises a terminal thiol group.

The sulfur-containing compounds used as curing agents contain at least two terminal groups that are reactive with michael acceptor groups. The sulfur-containing compound used as a curing agent in such compositions can comprise a polythioether including any of those disclosed herein. The sulfur-containing compound can have an average functionality of about 2 or any functionality from about 2 and about 6, such as from about 2 to about 4, or from about 2 to about 3.

The sulfur-containing compound used as the curing agent may be a small molecule such as a compound (molecular weight less than 400 daltons), a prepolymer, or a combination thereof. For example, the sulfur-containing compound can be a dithiol of formula (16) such as, for example, DMDO, a polythiol of formula (18), or a combination of any of the foregoing.

In certain embodiments, the sulfur compound-containing curing agent comprises a mixture of thiol-terminated polythioethers, such as, for example,3.1E。

in certain embodiments, the composition comprises a michael acceptor urethane-containing polythioether prepolymer provided by the present disclosure and a curing agent. The polythioether prepolymer includes any of those disclosed herein, such as a polythioether prepolymer of formula (6a), formula (6b), formula (8a), formula (8b), and a combination of any of the foregoing.

In certain embodiments of such compositions, the compositions comprise a michael acceptor-terminated urethane-containing prepolymer provided by the present disclosure and a curing agent selected from the group consisting of: a sulfur-containing compound comprising at least two terminal groups reactive with michael acceptor groups, a monomeric thiol, a polythiol, and a combination of any of the foregoing. In certain embodiments, the curing agent comprises a sulfur-containing compound comprising at least two terminal groups reactive with michael acceptor groups; in certain embodiments monomeric thiols; and in certain embodiments polythiols. In certain embodiments of such compositions, the curing agent comprises a sulfur-containing compound comprising at least two terminal groups reactive with michael acceptor groups and a compound having at least two terminal groups reactive with michael acceptor groups selected from the group consisting of monomeric thiols, polythiols, and combinations of any of the foregoing.

In certain embodiments, the sulfur-containing compound comprising at least two terminal groups reactive with michael acceptor groups is selected from polythioether compounds comprising at least two terminal groups reactive with michael acceptor groups. In certain embodiments, the terminal group reactive with a michael acceptor group is a terminal thiol group. In such embodiments, the thiol-terminated polythioether adduct can be selected from a thiol-terminated polythioether adduct of formula (15a), a thiol-terminated polythioether adduct of formula (15b), and a combination thereof.

In certain compositions, the curing agent comprises a monomeric polythiol. Monomeric polythiols refer to compounds having at least two terminal thiol groups. Examples of monomeric polythiols include dithiols of formula (16) and/or polythiols of formula (18).

In certain embodiments, the composition comprises a sulfur-containing curative provided by the present disclosure that is reactive with michael acceptor groups, and a michael acceptor-terminated urethane-containing prepolymer. In certain embodiments, the composition comprises a sulfur-containing curative provided by the present disclosure, a multifunctional michael acceptor, and a michael acceptor-terminated urethane-containing prepolymer.

In such compositions, the sulfur-containing curing agent comprises at least two terminal groups reactive with michael acceptor groups. In such compositions, the sulfur-containing curing agent may be selected from thiol-terminated sulfur-containing compounds.

In certain embodiments, the sulfur-containing curative may be selected such that the end groups are reactive with the multifunctional michael acceptor and the michael acceptor terminated urethane-containing prepolymer. In certain embodiments, the sulfur-containing curing agent comprises a terminal thiol group, including any of the thiol-terminated polythioethers disclosed herein.

When the composition comprises a multifunctional monomeric michael acceptor, any suitable monomeric michael acceptor having at least two michael acceptor groups may be used, such as, for example, divinyl sulfone or other michael acceptors, including any of those disclosed herein.

The multi-functional michael acceptor compound has at least two michael acceptor groups. The average Michael acceptor functionality of the multi-functional Michael acceptor may be from 2 to 6, 2 to 4, 2 to 3, and in some embodiments, from 2.05 to 2.5. In certain embodiments, the multi-functional michael acceptor is difunctional, such as divinyl ketone and divinyl sulfone. Michael acceptor compounds having a functionality greater than 2 may be prepared by reacting a compound having a michael acceptor group and a group reactive with the end group of a polyfunctionalizing agent, such as those disclosed herein, using appropriate reaction conditions.

In certain embodiments wherein a michael acceptor compound is used, the michael acceptor has a molecular weight of less than 600 daltons, less than 400 daltons, and in certain embodiments less than 200 daltons.

In certain embodiments, the michael acceptor-terminated urethane-containing prepolymer is selected from the group consisting of michael acceptor urethane-containing polythioether prepolymers of formula (6a), formula (6b), formula (8a), formula (8b), and combinations of any of the foregoing; the polyfunctional sulfur-containing adduct is selected from the group consisting of adducts of formula (15a), formula (15b), and combinations thereof; and the multifunctional monomeric michael acceptor is selected from compounds having two or more activated alkenyl groups, such as vinyl ketones or vinyl sulfones, such as divinyl sulfone.

In certain embodiments, at least one of the sulfur-containing curative and the michael acceptor urethane-containing prepolymer comprises a polythioether.

In certain embodiments, the composition comprises a sulfur-containing curative, a multifunctional michael acceptor, and a michael acceptor-terminated urethane-containing prepolymer, and a controlled release catalyst (including any of those disclosed herein).

In certain embodiments, the compositions provided by the present disclosure comprise an epoxy resin. Thus, in addition to the michael acceptor-terminated urethane-containing prepolymer, the composition may also include one or more polyepoxy curing agents. Examples of suitable epoxies include, for example, polyepoxide resins such as hydantoin diepoxide, diglycidyl ether of bisphenol-A, diglycidyl ether of bisphenol-F,epoxides such as DEN^TM438, certain epoxidized unsaturated resins, and combinations of any of the foregoing. Polyepoxides refer to compounds having two or more reactive epoxy groups. In certain embodiments, the polyepoxy resin may be combined with a michael acceptor-terminated urethane-containing prepolymer and then combined with a thiol-terminated curing agent.

In certain embodiments, the polyepoxy resin comprises an epoxy-functional compound. Examples of suitable epoxy-functional compounds include epoxy-functional sulfur-containing polyacetal compounds disclosed in U.S. Pat. No. 8,541,513 and epoxy-functional polysulfide compounds disclosed in U.S. Pat. No. 7,671,145. Generally, when used as a curing agent, the epoxy-functional compound has a molecular weight of less than about 2,000 daltons, less than about 1,500 daltons, less than about 1,000 daltons, and in certain embodiments, less than about 500 daltons.

In certain embodiments, the catalyst may be combined with the michael acceptor-terminated urethane-containing prepolymer shortly before use. In certain embodiments, the composition may comprise a latent or controlled release catalyst.

The compositions provided by the present disclosure may include one or more catalysts. Catalysts suitable for use in the reaction between a michael acceptor (such as an activated alkenyl group) and a thiol group include base catalysts such as amines. Examples of suitable amine catalysts include, for example, triethylenediamine (1, 4-diazabicyclo [2.2.2] octane, DABCO), Dimethylcyclohexylamine (DMCHA), Dimethylethanolamine (DMEA), bis- (2-dimethylaminoethyl) ether, N-ethylmorpholine, triethylamine, 1, 8-diazabicyclo [5.4.0] undecene-7 (DBU), Pentamethyldiethylenetriamine (PMDETA), Benzyldimethylamine (BDMA), N, N, N ' -trimethyl-N ' -hydroxyethyl-bis (aminoethyl) ether and N ' - (3- (dimethylamino) propyl) -N, N-dimethyl-1, 3-propanediamine.

In compositions comprising epoxides, the composition may comprise a base catalyst, including an amine catalyst, such as any of those disclosed herein.

The controlled release amine catalyst has little or no activity until released either chemically or physically. In certain embodiments, the controlled release amine catalyst may be released upon exposure to ultraviolet radiation, heat, ultrasound, or moisture.

In the case of a controlled release amine catalyst released by ultraviolet radiation or moisture, the amine catalyst comprises a blocking group that deblocks (deblock) after exposure to ultraviolet radiation or moisture to release or deblock the reactive amine catalyst. In matrix (matrix) encapsulant systems, the amine catalyst is trapped in the side chains of a crystalline or semi-crystalline polymer. At elevated temperatures, the polymer melts to allow the amine catalyst to diffuse into the composition to catalyze the reaction.

In certain embodiments, the controlled release catalyst comprises a controlled release amine catalyst. In certain embodiments, the controlled-release amine catalyst may be a controlled-release primary amine catalyst, a controlled-release secondary amine catalyst, or a controlled-release tertiary amine catalyst. Examples of suitable primary amine catalysts include, for example, C_3-10Aliphatic primary amines such as heptanamine (heptanamine), hexylamine, and octylamine (octamine). Examples of suitable secondary amine catalysts include, for example, cycloaliphatic diamines such as754 and aliphatic diamines such as1000. Examples of suitable tertiary amine catalystsSub-groups include, for example, N, N-Dimethylethanolamine (DMEA), Diaminobicyclooctane (DABCO), Triethylenediamine (TEDA), bis (2-dimethylaminoethyl) ether (BDMAEE), N-ethylmorpholine, N ', N' -dimethylpiperazine, N, N, N ', N', N "-pentamethyl-diethylene-triamine (PMDETA), N, N '-Dimethylcyclohexylamine (DMCHA), N, N-Dimethylbenzylamine (DMBA), N, N-dimethylethylamine, N, N', N", N "-pentamethyl-dipropylene-triamine (PMDPTA), triethylamine, and 1- (2-hydroxypropyl) imidazole. Other suitable amine catalysts include amidine catalysts such as Tetramethylguanidine (TMG), Diazabicyclononene (DBN), Diazabicycloundecene (DBU), and imidazole; and bicyclic guanidines such as 1,5,7, -triazabicyclo [4.4.0]Dec-5-ene (TBD) and 1,5, 7-triazabicyclo [4.4.0]Dec-5-ene, 7-Methyl (MTBD).

In certain embodiments, the amine catalyst is selected from DBU, DABCO, Isophoronediamine (IPDA), C_6-10Primary amines, and combinations of any of the foregoing.

The composition may comprise one or more different types of amine catalysts.

When released, the controlled release amine catalysts provided by the present disclosure catalyze a reaction between a compound containing at least two terminal groups reactive with michael acceptor groups and a compound containing at least two michael acceptor groups (such as the michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure).

In the controlled release compositions provided by the present disclosure, the pot life of the composition may be greater than 2 weeks if the catalyst is not released. When the catalyst is released by a chemical, photochemical or physical mechanism, the cure time may be less than 72 hours, less than 60 hours, less than 48 hours, less than 36 hours, and in some embodiments less than 24 hours. Without heating and in the presence of ambient moisture, the cure time may be several days, such as, for example, 7 days.

Certain compositions provided by the present disclosure comprise a photolabile catalyst. In such systems, ultraviolet radiation deblocks a blocked amine catalyst that catalyzes the michael addition reaction between a compound containing at least two terminal groups reactive with michael acceptor groups and a compound containing at least two michael acceptor groups. In certain embodiments, the ultraviolet radiation initiates a reaction that occurs over time, such as, for example, several hours. Slow cure can be used to improve surface adhesion and extend pot life to provide longer run times.

The photolabile amine comprises a photolabile moiety bonded to the amine.

In certain embodiments, the photolabile catalyst comprises CGI 90(BASF), which upon UV activation yields the tertiary amine, 1, 5-diazabicyclo (4.3.0) non-5-ene (DBN). Other suitable photolabile amines are disclosed in international publication No. WO 2003/033500 and the references cited therein.

In compositions comprising a photolabile amine catalyst, the photolabile amine catalyst may comprise from 0.1 wt% to 5 wt% of the composition, from 0.3 wt% to 2 wt% of the composition, and in certain embodiments, from 0.5 wt% of the composition to 1 wt% of the composition.

In certain embodiments, the controlled release amine catalyst comprises a moisture-releasing blocked amine catalyst. In such systems, the blocked amine catalyst may deblock in the presence of moisture to release an amine catalyst capable of catalyzing the michael addition reaction. Examples of moisture-releasing blocked amine catalysts include ketimines, enamines, oxazolidines, aldimines, and imidazolidines. In the presence of moisture, a blocking group, e.g., ketimine, enamine, oxazolidine, aldimine, or imidazolidine blocking group(s), reacts with water to provide a catalytic amine catalyst and a ketone or alcohol.

In certain embodiments, the composition comprising the moisture-releasing amine catalyst comprises 0.1 wt% to 2 wt% water, 0.2 wt% to 1.5 wt% water, and in certain embodiments, 0.5 wt% to 1 wt% water.

In certain embodiments, the moisture-releasing blocked amine catalyst releases a primary amine, a secondary amine, and in certain embodiments a tertiary amine. In certain embodiments, the moisture-releasing blocked amine catalyst isA139 which is a blocked cycloaliphatic diamine. In certain embodiments, the deblocked amine is isophorone diamine (IPDA).

In compositions comprising the moisture-releasing amine catalyst, the moisture-releasing amine catalyst can comprise from 0.1 wt% to 4 wt% of the composition, from 0.5 wt% to 3 wt% of the composition, and in certain embodiments, from 1 wt% of the composition to 2 wt% of the composition.

In certain embodiments, the ratio of wt% water to moisture-released amine catalyst (wt%) in the compositions provided by the present disclosure (wt%/wt%) can be 1 to 4, 1 to 2, and in certain embodiments, 1 to 1.

The composition comprising the moisture-releasing blocked amine catalyst, in addition to being stored at low temperatures, can be so stored as to prevent exposure to ambient moisture.

Matrix encapsulation is a process by which droplets or particles of liquid or solid material are trapped in the side chains of a crystalline polymer. With increasing temperature, the crystalline polymer becomes amorphous and releases droplets or particles into the medium. The present disclosure provides matrix encapsulants comprising a crystalline matrix material having droplets or particles comprising an amine catalyst. Thus, the rate of reaction is controlled to some extent by the temperature-dependent diffusion of the amine catalyst from the crystalline polymer. Crystalline polymers may have a well-defined (sharp), well-defined melting point or may exhibit a range of melting points. The use of waxy (wax) polymers for encapsulating amine catalysts in michael addition compositions is disclosed in U.S. patent publication No. 2007/0173602.

Suitable example matrix encapsulants includePolymers (Air Products), such as13-1 and13-6。the properties of the polymers are disclosed in Lowry et al, "Cure evaluation oflatex curing agents for thermal set Resin applications, "presented in the thermo resins Association Meeting, Chicago, IL, 9.9.16.2008.

The matrix encapsulant may be selected to release the amine catalyst followed by a brief high temperature exposure such as for less than 10 minutes, less than 5 minutes, or less than 2 minutes. During this brief temperature excursion, the amine catalyst is released from the matrix and diffuses into the reactive polymer component. The composition may be heated during the curing process or may be maintained at ambient temperature. When held at ambient temperature, the released amine catalyst composition may cure in less than 2 hours, in less than 4 hours, and in certain embodiments, in less than 6 hours.

The amine catalyst may be incorporated into the matrix encapsulant by blending at a temperature above the melting temperature of the matrix encapsulant, rapidly cooling the mixture, and grinding the solids into a powder. In certain embodiments, the average particle size is less than 200 μm, less than 150 μm, less than 100 μm, less than 50 μm, and in certain embodiments, less than 25 μm.

In certain embodiments, the composition may comprise 0.1 wt% to 25 wt%, 1 wt% to 15 wt%, and in certain embodiments, 5 wt% to 10 wt% of a matrix encapsulant comprising an amine catalyst. This is associated with about 0.01 wt% to 2 wt%, 0.05 wt% to 1.5 wt%, and in certain embodiments, 0.5 wt% to 1 wt% of the amine catalyst.

In certain embodiments, matrix encapsulants suitable for use in the compositions provided by the present disclosure include a ratio of 1 to 15, 2 to 10, and in certain embodiments, 5 to 8 wt% amine catalyst to wt% matrix polymer (wt%/wt%).

The group provided by the present disclosureThe compound may include one or more catalysts. The catalyst may be selected to be suitable for the curing chemistry employed. In certain embodiments, for example, when curing thiol-terminated bis (sulfonyl) alkanol-containing polythioethers or prepolymers and polyepoxides, the catalyst can be an amine catalyst. The curing catalyst may be present in an amount of 0.1 to 5 weight percent, based on the total weight of the composition. Suitable exemplary catalysts include 1, 4-diazabicyclo [2.2.2]Octane (C)Commercially available from Air Products, Chemical Additives Division, Allentown, Pa.) and DMP-(Accelerator composition comprising 2,4, 6-tris (dimethylaminomethyl) phenol examples of other suitable amine catalysts include, for example, triethylenediamine (1, 4-diazabicyclo [2.2.2]]Octane, DABCO), Dimethylcyclohexylamine (DMCHA), Dimethylethanolamine (DMEA), bis- (2-dimethylaminoethyl) ether, N-ethylmorpholine, triethylamine, 1, 8-diazabicyclo [5.4.0]]Undecene-7 (DBU), Pentamethyldiethylenetriamine (PMDETA), Benzyldimethylamine (BDMA), N ' -trimethyl-N ' -hydroxyethyl-bis (aminoethyl) ether, and N ' - (3- (dimethylamino) propyl) -N, N-dimethyl-1, 3-propanediamine.

In certain embodiments, the present disclosure provides compositions comprising one or more than one adhesion promoter. One or more additional adhesion promoters may be present in the composition in an amount of from 0.1 wt% to 15 wt%, less than 5 wt%, less than 2 wt%, and in certain embodiments, less than 1 wt%, based on the total dry weight of the composition. Examples of adhesion promoters include phenolics, such asPhenolic resins, and organosilanes, such as epoxy, mercapto or amino functional silanes, such asA-187Andand A-1100. Other useful adhesion promoters are known in the art.

In certain embodiments, the present disclosure provides compositions comprising ethylenically unsaturated silanes, such as, for example, sulfur-containing ethylenically unsaturated silanes, which can improve adhesion of the cured sealant to a metal substrate. The term sulfur-containing ethylenically unsaturated silane as used herein refers to a molecular compound that contains within the molecule (i) at least one sulfur (S) atom, (i i) at least one, and in some cases at least two, ethylenically unsaturated carbon-carbon bonds, such as a carbon-carbon double bond (C ═ C); and (iii) at least one silane group, -Si (-R)_m(-OR)_3-mWherein each R is independently selected from hydrogen, alkyl, cycloalkyl, aryl, and others, and m is selected from 0, 1, and 2. Examples of ethylenically unsaturated silanes are disclosed in U.S. publication No. 2012/0040104, which is incorporated by reference in its entirety.

In certain embodiments, the compositions provided by the present disclosure may be cured using actinic radiation. Examples of compositions comprising polythioether compositions curable with actinic radiation are disclosed in U.S. publication No. 2012/0040104. In addition to the adhesion promoting adducts and one or more sulfur-containing polymers, such as thiol-terminated sulfur-containing polymers, provided by the present disclosure, such compositions can further include polyenes such as polyvinyl ethers, including, for example, polyvinyl ethers of formula (17).

The compositions provided by the present disclosure may include one or more catalysts.

The compositions provided by the present disclosure may comprise one or more additional components suitable for use in aerospace sealants and depend, at least in part, on the desired performance characteristics of the sealant cured under the conditions of use.

In certain embodiments, the present disclosure provides compositions comprising one or more than one adhesion promoter. One or more additional adhesion promoters may be present in an amount of from 0.1 wt% to 15 wt%, less than 5 wt%, less than 2 wt%, and in certain embodiments,less than 1 wt% is present in the composition based on the total dry weight of the composition. Examples of adhesion promoters include phenolics, such asPhenolic resins, and organosilanes, such as epoxy, mercapto or amino functional silanes, such asA-187 andand A-1100. Other useful adhesion promoters are known in the art.

The compositions provided by the present disclosure may include one or more different types of fillers. Suitable fillers include those known in the art, including inorganic fillers such as carbon black and calcium carbonate (CaCO)₃) Silica, polymer powders and light fillers. Suitable lightweight fillers include, for example, those described in U.S. patent No. 6525168. In certain embodiments, the composition includes from 5 wt% to 60 wt% of a filler or combination of fillers, from 10 wt% to 50 wt% and in certain embodiments from 20 wt% to 40 wt%, based on the total dry weight of the composition. The compositions provided by the present disclosure may further include one or more colorants, thixotropic agents, accelerators, flame retardants, adhesion promoters, solvents, masking agents, or a combination of any of the foregoing. As can be appreciated, the fillers and additives used in the composition can be selected to be compatible with each other as well as the polymer components, curing agent and or catalyst.

In certain embodiments, the compositions provided by the present disclosure include low density filler particles. As used herein, low density, when used in reference to such particles, means that the particles have a specific gravity of no greater than 0.7, in certain embodiments no greater than 0.25, and in certain embodiments no greater than 0.1. Suitable lightweight filler particles often fall into two categories-microspheres and amorphous particles. The microspheres may have a specific gravity of 0.1 to 0.7 and include, for example, polystyrene foam, polyacrylate and polyolefin microspheresAnd dioxide microspheres having a particle size of 5 microns to 100 microns and a specific gravity of 0.25Other examples include alumina/silica microspheres having a particle size of 5 microns to 300 microns and a specific gravity of 0.7Aluminum silicate microspheres having a specific gravity of about 0.45 to about 0.7Calcium carbonate coated polyvinylidene copolymer microspheres having a specific gravity of 0.13 (6001AE), and calcium carbonate-coated acrylonitrile copolymer microspheres such asE135 having an average particle size of about 40 μm and a density of 0.135g/cc (Henkel). Suitable fillers for reducing the specific gravity of the composition include, for example, hollow microspheres such asMicrospheres (available from akzo nobel) orLow density polymeric microspheres (obtained from Henkel). In certain embodiments, the compositions provided by the present disclosure include lightweight filler particles comprising an outer surface coated with a thin coating, such as described in U.S. publication No. 2010/0041839 [0016 ]]-[0052]Those of the paragraph, the referenced portion of which is incorporated herein by reference.

In certain embodiments, the low density filler comprises less than 2 wt%, less than 1.5 wt%, less than 1.0 wt%, less than 0.8 wt%, less than 0.75 wt%, less than 0.7 wt%, and in certain embodiments, less than 0.5 wt% of the composition, wherein the wt% is based on the total dry solids weight of the composition.

In certain embodiments, the present disclosure provides compositions comprising at least one filler effective to reduce the specific gravity of the composition. In certain embodiments, the specific gravity of the composition is from 0.8 to 1, from 0.7 to 0.9, from 0.75 to 0.85 and in certain embodiments about 0.8. In certain embodiments, the specific gravity of the composition is less than about 0.9, less than about 0.8, less than about 0.75, less than about 0.7, less than about 0.65, less than about 0.6, and in certain embodiments, less than about 0.55.

The composition may also include any number of additives as desired. Examples of suitable additives include plasticizers, pigments, surfactants, adhesion promoters, thixotropic agents, flame retardants, masking agents, and accelerators (such as amines, including 1, 4-diaza-bicyclo [2.2.2]The octane is a mixture of the octane and the octane,) And combinations of any of the foregoing. When used, additives may be present in the composition in an amount of, for example, about 0 wt% to 60 wt%. In certain embodiments, the additives may be present in the composition in an amount of about 25 wt% to 60 wt%.

The compositions provided by the present disclosure may be used in, for example, sealant, coating, encapsulant, and encapsulation (potting) compositions. Sealants include compositions capable of producing films that have the ability to withstand operating conditions such as humidity and temperature, and that at least partially block the transmission of materials such as water, fuel, and other liquids and gases. The coating composition includes a coating applied to the surface of the substrate to, for example, improve substrate properties such as appearance, adhesion, wetting, corrosion resistance, abrasion resistance, fuel resistance, and/or abrasion resistance. Encapsulating compositions include materials that can be used in electronic components to provide shock and vibration resistance and to repel moisture and corrosive agents. In certain embodiments, the sealant compositions provided by the present disclosure are useful, for example, as aerospace sealants and as fuel tank liners.

In certain embodiments, the composition containing the michael acceptor-terminated urethane-containing prepolymer is formulated as a sealant.

In certain embodiments, compositions, such as sealants, may be provided as multi-package compositions, e.g., two-package compositions, wherein one package comprises one or more thiol-terminated polythioethers as provided by the present disclosure and a second package comprises one or more multi-functional michael acceptor-terminated urethane-containing prepolymers as provided by the present disclosure. Additives and/or other materials may be added to any of the packages as desired or needed. The two packages may be combined and mixed prior to use. In certain embodiments, the pot life of the one or more mixed thiol-terminated polythioethers and epoxides is at least 30 minutes, at least 1 hour, at least 2 hours, and in certain embodiments, greater than 2 hours, where pot life refers to the period of time that the mixed composition remains suitable for use as a sealant after mixing.

The compositions (including sealants) provided by the present disclosure may be applied to any of a variety of substrates. Examples of substrates to which the composition may be applied include metals such as titanium, stainless steel, and aluminum, any of which may be anodized, primed, organic coated, or chromate coated; epoxy; a polyurethane; graphite; a glass fiber composite material;acrylic acids; and a polycarbonate. In certain embodiments, the compositions provided by the present disclosure may be applied to a coating on a substrate, such as a polyurethane coating.

The compositions provided by the present disclosure may be applied directly onto the substrate surface or onto an underlying layer by any suitable coating method.

Further, methods of sealing an aperture using the compositions provided by the present disclosure are provided. These methods include, for example, applying a composition provided by the present disclosure to a surface to seal an aperture, and curing the composition. In certain embodiments, a method of sealing an aperture comprises applying a sealant composition provided by the present disclosure to a surface defining an aperture and curing the sealant to provide a sealed aperture.

In certain embodiments, the composition may be cured under ambient conditions, wherein ambient conditions refer to a temperature of 20 ℃ to 25 ℃ and atmospheric humidity. In certain embodiments, the composition may be cured under conditions that include a temperature of 0 ℃ to 100 ℃ and a humidity of 0% relative humidity to 100% relative humidity. In certain embodiments, the composition may be cured at higher temperatures, such as at least 30 ℃, at least 40 ℃, and in certain embodiments at least 50 ℃. In certain embodiments, the composition may be cured at room temperature, e.g., 25 ℃. In certain embodiments, the composition may be cured after exposure to actinic radiation, such as ultraviolet radiation. It will also be appreciated that the method may be used to seal holes on aerospace vehicles, including aircraft and aerospace vehicles.

In certain embodiments, the composition achieves tack-free cure at a temperature of less than about 200 ° F for less than about 2 hours, less than about 4 hours, less than about 6 hours, less than about 8 hours, and in certain embodiments, less than about 10 hours.

The time to form a viable seal using the curable composition of the present disclosure may depend on several factors, which are understood by those skilled in the art, and are defined by the requirements of the applicable standards and specifications. Typically, the curable compositions of the present disclosure develop adhesive strength between 24 hours and 30 hours and 90% of full adhesion strength between 2 days and 3 days after mixing and application to a surface. Typically, the full adhesion strength and other properties of the cured compositions of the present disclosure are fully developed within 7 days after the curable composition is mixed and applied to a surface.

For aerospace sealant applications, it is desirable that the sealant meet the requirements of Mil-S-22473E (sealant grade C) at a cured thickness of 20 mils, exhibit an elongation of greater than 200%, a tensile strength of greater than 250psi, and excellent fuel resistance, and maintain these properties over a wide temperature range of-67 ° f to 360 ° f. Typically, the visual appearance of the sealant is not an important attribute. Prior to curing, it is desirable that the mixed components have a useful run time or pot life of at least 24 hours and have a cure time within a 24 hour pot life. Useful run time or pot life refers to the period of time after the catalyst is released that the composition remains viable for ambient temperature application. In certain embodiments, the compositions provided by the present disclosure have a pot life of at least 6 hours, at least 12 hours, at least 18 hours, at least 24 hours, and in certain embodiments greater than 24 hours after catalytic amine release. In certain embodiments, the compositions provided by the present disclosure cure after a pot life of less than 6 hours, less than 12 hours, less than 18 hours, less than 24 hours, less than 48 hours, and in certain embodiments less than 72 hours after a useful run time.

The cured compositions, e.g., cured sealants, disclosed herein exhibit acceptable properties for use in aerospace applications. In general, it is desirable that sealants used in aerospace applications exhibit the following properties: peel strength measured on Aerospace Material Specification (AMS)3265B substrates under dry conditions after 7 days soaking in JRF type I and after soaking in a 3% NaCl solution according to AMS3265B test specification is greater than 20 pounds per linear inch (pli); a tensile strength of 300 pounds per square inch (psi) to 400 psi; tear strength greater than 50 pounds per linear inch (pl i); elongation of 250-300%; and a hardness greater than 40 durometer a. These and other cured sealant properties suitable for aerospace applications are disclosed in AMS3265B, which is incorporated by reference in its entirety. It is also desirable that the compositions for aerospace and aircraft applications of the present disclosure, when cured, exhibit a percent volume swell of no greater than 25% after soaking in JRF type I for 1 week at 60 ℃ (140 ° f) and ambient pressure. Other properties, ranges and/or thresholds may be suitable for other sealant applications.

Thus, in certain embodiments, the compositions provided by the present disclosure are fuel-resistant. As used herein, the term "fuel resistant" means a composition that, when applied to a substrate and cured, can provide a cured product, e.g., a sealant, that exhibits a percent volume swell of no greater than 40%, in some cases no greater than 25%, in some cases no greater than 20%, and in still other cases no greater than 10% after immersion in Jet Reference Fluid (JRF) type I for 1 week at 140 ° f (60 ℃) and ambient pressure according to methods similar to those described in ASTM D792 (american society for testing and materials) or AMS 3269 (aerospace material specifications). Jet ReferenceFluid JRF type I, used for determining fuel resistance, has the following composition: toluene: 28% ± 1% by volume; cyclohexane (technical grade): 34% vol ± 1% vol; isooctane: 38% ± 1% by volume; and tert-dibutyl disulfide: 1% ± 0.005% by volume (see AMS 2629, 7 month 1 day release 1989, § 3.1.1 et al, available from SAE (society of automotive engineers)).

In certain embodiments, the compositions provided herein provide cured products, such AS sealants, that exhibit a tensile elongation of at least 100% and a tensile strength of at least 400psi when measured according to the procedures described in AMS3279, § 3.3.17.1, test procedures AS5127/1, § 7.7.

In certain embodiments, cured sealants comprising the compositions provided by the present disclosure meet or exceed the requirements of aerospace sealants as described in AMS 3277.

Also disclosed are apertures, including apertures of aerospace vehicles, sealed with the compositions provided by the disclosure.

Examples

Embodiments provided by the present disclosure are further illustrated with reference to the following examples describing the synthesis, performance, and use of certain michael acceptor-terminated urethane-containing prepolymers provided by the present disclosure. It will be apparent to those skilled in the art that many modifications, both to materials and methods, may be practiced without departing from the scope of the disclosure.

Example 1

A thiol-terminated polythioether adduct was synthesized.

Thiol-terminated polythioethers were prepared according to example 1 of U.S. Pat. No.6,172,179. In a 2-L flask, 524.8g (3.32mol) of diethylene glycol divinyl ether (DEG-DVE) and 706.7g (3.87mol) of dimercaptodioxaoctane (DMDO) were mixed with 19.7g (0.08mol) of triallyl cyanurate (TAC) and heated to 77 ℃. To the reaction mixture was added 4.6g (0)024mol) of azodinitrile free-radical catalyst: (2,2' -azobis (2-methylbutyronitrile)). The reaction proceeded substantially to completion after 2 hours to provide 1,250g (0.39mol, yield 100%) of T_gIs a liquid thiol-terminated polythioether adduct at-68 ℃ and a viscosity of 65 poise. The adduct is pale yellow and has a low odour.

Example 2

Synthesis of H₁₂MDI-terminated polythioether adducts

A1-liter, 4-neck round bottom flask was equipped with a mantle (mantle), thermocouple, temperature controller, nitrogen line, mechanical stirrer and dropping funnel. A flask was charged with a thiol-terminated polythioether (652.30g) prepared according to example 1 of U.S. Pat. No.6,172,179 (see previous paragraph). The flask was heated to 71 ℃ under nitrogen and stirred at 300 rpm. 4-hydroxybutyl vinyl ether (47.40g) and (b) were added via a dropping funnel over 1 hour(1.19g) the mixture was added to the flask. The reaction mixture was held at 71 ℃ for 41 hours at which point the reaction was complete. After this, the reaction apparatus was then equipped with a vacuum line and the product was heated to 94 ℃. Heating was continued under vacuum for 1.3 hours. After vacuum treatment, a pale yellow, viscous polythioether polyol (678.80g) was obtained. The polythioether polyol (hydroxyl terminated polythioether adduct) had a hydroxyl number (hydroxyynumber) of 31.8 and a viscosity of 77 poise.

The polythioether polyol (300.03g) was then added to a 500-mL, 4-necked, round-bottomed flask. The flask was equipped with a cap, thermocouple, temperature controller, inlet to provide positive pressure of nitrogen, and mechanical stirrer (PTFE paddle and bearing). The polythioether polyol is stirred at about 200rpm and heated to 76.6 ℃ (170 ° F), followed by addition(H₁₂MDI) (82.00g) and dibutyltin dilaurate in methylethyl0.01% solution in ketone (3.90 g). The reaction mixture was kept at 76.6 ℃ for 7h and then cooled to room temperature. A1% solution of benzyl chloride dissolved in methyl ethyl ketone (3.80g) was then added to the reaction mixture. Obtained H₁₂The isocyanate content of the MDI-terminated polythioether adduct (isocyanate-terminated urethane-containing polythioether adduct) was 3.9%.

Example 3

Synthesis of bis (vinylsulfonyl) terminated urethane-containing polythioether prepolymer

In a 300mL, 3-necked round bottom flask (equipped with stirrer, thermal probe and nitrogen inlet) were added 100g of the isocyanate-terminated urethane-containing polythioether adduct described in example 2 and 22g of 3-bis (vinylsulfonyl) -2-propanol and the reaction temperature was set to 85 ℃. Once the temperature reached 85 ℃, 3-bis (vinylsulfonyl) -2-propanol was homogeneously dissolved in the polymer. 40 μ L of tin catalyst (DABCO T-12, dibutyltin dilaurate) was then added to catalyze the reaction of the isocyanate groups of the polymer with the hydroxyl groups of 3-bis (vinylsulfonyl) -2-propanol. After 15min, the reaction temperature reached 109 ℃. After completion of the reaction in about 60 minutes, the reaction mixture was removed from the heat (heat), poured out of the flask, and cooled.

Example 4

Preparation of Encapsulated catalysts

Mixing 9.3 g of13-6 (from Air Products and Chemicals, Allentown, Pa.) and 0.7 grams of isophoronediamine (3-aminomethyl-3, 5, 5-trimethylcyclohexylamine,IPD, Evonik Industries) was blended at 80 ℃ for 30 minutes. The mixture was rapidly cooled to room temperature and then ground into a powder having an average particle size of 25 microns.

Example 5

Michael acceptor-terminated urethane-containing prepolymer sealants

The thiol-terminated polythioether adduct described in example 1 (4.76g), the bis (vinylsulfonyl) terminated urethane-containing polythioether prepolymer described in example 3 (3.95g), the encapsulated amine catalyst (0.11g, Novacure)^TMHX-3722), and the encapsulated amine catalyst described in example 4 (10mg) were mixed with DAC 600FVZ Speed Mixer at 2300rpm for 30 seconds. A portion of the mixture was allowed to stand at room temperature (sit) for 2 days. The material remained uncured for 2 days.

The second portion of the mixture was heated at 180 ° F for 5 minutes and then allowed to remain at room temperature. The material became tack-free within 2.5 hours and cured completely to a solid elastomer within 16 hours.

Finally, it should be noted that there are alternative ways of implementing the embodiments disclosed herein. Accordingly, the present embodiments are to be considered as illustrative and not restrictive. Furthermore, the claims are not to be limited to the details given herein, and are to be given their full scope and equivalents.

Claims

1. A michael acceptor-terminated urethane-containing prepolymer comprising the reaction product of reactants comprising:

(a) an isocyanate-terminated urethane-containing adduct, wherein the isocyanate-terminated urethane-containing adduct comprises an isocyanate-terminated urethane-containing polythioether adduct, an isocyanate-terminated urethane-containing polysulfide adduct, or a combination thereof; and

(b) bis (vinylsulfonyl) alkanols.

2. The prepolymer of claim 1, wherein the isocyanate-terminated urethane-containing adduct comprises the reaction product of reactants comprising:

(a) a hydroxyl terminated sulfur-containing adduct; and

(b) a diisocyanate.

3. The prepolymer of claim 2, wherein the hydroxyl-terminated sulfur-containing adduct comprises a hydroxyl-terminated polythioether adduct of formula (12a), a hydroxyl-terminated polythioether adduct of formula (12b), or a combination thereof:

R⁶-S-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-R⁶ (12a)

{R⁶-S-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-V’-}_zB (12b)

wherein,

each R¹Independently selected from C_2-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-10Alkanecycloalkanediyl, C_5-8Heterocycloalkanediyl and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each R³Independently selected from hydrogen and methyl; and

each R²Independently selected from C_1-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-14Alkanecycloalkanediyl and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which s, q, R, R³And X is as for R¹As defined;

m is an integer from 0 to 50;

n is an integer from 1 to 60; and

p is an integer from 2 to 6;

each R⁶Is independently selected from-CH₂-CH₂-O-R¹³-OH, wherein each R¹³Is C_2-10An alkanediyl group; and

z is an integer from 3 to 6; and

each V is a moiety comprising a terminal group reactive with a thiol; and

each-V' -results from the reaction of-V with a thiol.

4. The prepolymer of claim 2, wherein the hydroxyl-terminated sulfur-containing adduct comprises the reaction product of reactants comprising:

(a) a thiol-terminated sulfur-containing adduct; and

(b) a hydroxy vinyl ether.

5. The prepolymer of claim 4, wherein the thiol-terminated sulfur-containing adduct comprises a thiol-terminated polythioether adduct of formula (15a), a thiol-terminated polythioether adduct of formula (15b), or a combination thereof:

HS-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-SH (15a)

{HS-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n-S-V’-}_zB (15b)

wherein,

each R¹Independently selected from C_2-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-14Alkanecycloalkanediyl, C_5-8Heterocycloalkanediyl and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each R³Independently selected from hydrogen and methyl; and

m is an integer from 0 to 50;

n is an integer from 1 to 60;

p is an integer from 2 to 6;

z is an integer from 3 to 6; and

each V is a moiety comprising a terminal group reactive with a thiol; and

each-V' -results from the reaction of-V with a thiol.

6. The prepolymer of claim 1, wherein the bis (vinylsulfonyl) alkanol comprises 1, 3-bis (vinylsulfonyl) -2-propanol.

7. A michael acceptor-terminated urethane-containing prepolymer comprising a prepolymer of formula (6a), a prepolymer of formula (6b), or a combination thereof:

wherein,

w is an integer from 1 to 100;

each R¹³Independently comprise C_2-10An alkanediyl group;

each R²⁰A core independently comprising a diisocyanate;

each R³⁰Independently comprises the structure of formula (9):

-O-CH(-R¹⁰-S(O)₂-CH＝CH₂)₂ (9)

wherein R is¹⁰Is C_1-3An alkane-diyl group;

each R⁵⁰A core independently comprising a sulfur-containing prepolymer;

-O-R¹³-O-(CH₂)₂-S-R⁵⁰-S-(CH₂)₂-O-R¹³-O- (7)

z is an integer from 3 to 6; and

each V is a moiety comprising a terminal group reactive with a thiol; and

each-V' -results from the reaction of-V with a thiol.

8. The prepolymer of claim 7, wherein each R is⁵⁰A structure comprising formula (5):

-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n- (5)

wherein,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each R³Independently selected from hydrogen and methyl; and

m is an integer from 0 to 50;

n is an integer from 1 to 60; and

p is an integer from 2 to 6.

9. A composition comprising:

the michael acceptor-terminated urethane-containing prepolymer of claim 1 or claim 7; and

an amine catalyst.

10. The composition of claim 9, comprising a thiol-terminated sulfur-containing adduct.

11. The composition of claim 10, wherein the thiol-terminated sulfur-containing adduct comprises a thiol-terminated polythioether, a thiol-terminated polysulfide, a thiol-terminated sulfur-containing polyformal, or a combination of the foregoing.

12. The composition of claim 9, wherein the amine catalyst comprises a controlled release amine catalyst.

13. The composition of claim 9 formulated as a sealant.

14. A cured sealant prepared from the composition of claim 13.

15. An aerospace vehicle comprising the cured sealant of claim 14.

16. The prepolymer of claim 1, wherein

(a) An isocyanate-terminated urethane-containing polythioether adduct comprises a moiety of formula (5):

-R¹-[-S-(CH₂)_p-O-(R²-O)_m-(CH₂)₂-S-R¹-]_n- (5)

wherein,

each R is¹Is independently selected fromC_2-10Alkanediyl, C_6-8Cycloalkanediyl group, C_6-14Alkanecycloalkanediyl, C_5-8Heterocyclic alkanediyl, and- [ (-CHR)³-)_s-X-]_q-(-CHR³-)_r-, in which,

s is an integer from 2 to 6;

q is an integer of 1 to 5;

r is an integer from 2 to 10;

each R³Independently selected from hydrogen and methyl; and

m is an integer from 0 to 50;

n is an integer from 1 to 60; and

p is an integer from 2 to 6; and

(b) the bis (vinylsulfonyl) alkanol has the structure:

CH₂＝CH–S(O)₂–R¹⁰–CH(–OH)–R¹⁰–S(O)₂–CH＝CH₂

wherein each R¹⁰Independently is C_1-3An alkanediyl group.